The last sentence only follows if one assumes that having mechanically discrete and distinctive abilities = is a spell caster.
Even in AD&D this wasn't true - see eg the martial arts manoeuvres in OA, or a monk's special abilities. In 3E it's not true (see eg feats and some class abilities).
And it's certainly not conceptually true.
The issue is that with a list of spells, or a list of feats, you've got
one list of abilities that's fairly universal across the entire game. And everybody's basically pulling from the same list. You play the game for a year, and you're going to have about 80% of the feats and spells more or less memorized.
Even better, they're all in the PHB. That means it's not just on you as the DM to get every ability right. Your players can correct you, and help you out by reading the spell description. Nobody's casting a
fireball that targets Fort, or has a 50' radius, or uses d10s for damage, or is not a sphere, or has one of two dozen rider effects.
This is a complete non-sequitur. If all I read are decent books, each is unique and each seems special!
I meet a lot of people in my job - all are unique, many seem special.
In the context of a FRPG combat, an ability is "special" if, in play, it (i) creates a cool image, and (ii) makes the players think about how they're going to deal with it, and if, after the vent, it (iii) remains memorable. I find this to be the case for a good number of 4e monsters: they create cool images during play, they force the players to think, and the whole event is memorable. The issues of "degree of uniqueness" has no real bearing on this, except that stuff that is the same tends not to be as memorable, because it blurs together in the memory.
If every book you read is detective novels, they're going to get pretty dull. If the only customers you meet in your job are doctors or teachers or police officers, again, they're going to start to have a bit of a sameness to them. It will get difficult to tell them apart.
It's like if your only entertainment was a TV that played nothing but 90s sitcoms all day every day. Friends, Seinfeld, Roseanne, Frasier, Home Improvement, Everybody Loves Raymond, Wings, Martin, Sabrina, Fresh Prince, Boy Meets World, etc. Maybe they're very good sitcoms. Maybe you like them. Maybe they're episodes you've never seen before. But you know they're all structured exactly the same. The plot will vary, but the pacing, themes, general narrative structure, and often the humor is all identical. That's going to get very tiresome.
You're right that those factors you list can make a combat memorable, but when
every combat has the players do those three things then combat will still stop being memorable. Your combats essentially become a Michael Bay movie. Very exciting things happen all the time. Wow, more explosions and slow motion CGI. Just like the last one. And the one before that. And the one before that. You watch the first Transformers movie, and it's very exciting. You watch the next three, and they all blend together. You can do this pretty easily with any movie marathon. Sit down and watch Iron Man 3, Captain America 2 and 3, and Avengers 1 and 2. By the end, the plots and storylines all blend together. If, instead, you break things up and watch other movies or take a break between them of a few months, you allow the memorably elements to be memorable. I feel like you can't do that with 4e because of the way monsters are built.
Now, yes,
you may find 4e's monsters to be distinctive enough, but
I certainly did not. I found that they all followed the same template, and that got very dull after awhile. And from the discussions I've had, the sentiment was shared in my playgroup. By the end, I felt like there were only really 5 monsters in the game: Brute, Artillery, Soldier, Controller, and Skirmisher/Lurker (which often played the same, IMX). Everything else was just whatever damage type they dealt and whatever 1 round or save ends rider effects their abilities had. The stats were otherwise basically locked to the CR of the creature. Toward the end of my group's play in 4e, the only distinction the players sought was: "What role is this monster?" That was the only really useful "hidden" information. Once you knew that, the tactical choices were pretty obvious and, therefore, not particularly difficult.
You don't have to agree with me. I'm not proving things deductively here. I'm stating my opinion, and relating my experience.
If you state it very carefully, maybe, you can present it as an honest opinion. You have to be clear that its your personal subjective experience of 'feel' that at issue, and that the mechanics do, in fact, present separate & different casting and non-casting options. Once it's clear that the objection is not that 'fighters cast spells,' but that fighters & spells casters are not differentiated by the former being mechanically inferior, and that changes the feel of a game where traditionally such was the case.
I really don't feel like it's out of line to expect that, unless I'm citing references from the books or quoting others to reinforce my argument that I need to explicitly and repeatedly state that I'm relating my personal opinion. There is some burden for that determination placed on the reader. Yes, it can be more clear when someone uses the phrase, "In my opinion," but that's not a rhetorical requirement for an opinion. Frankly, it should have been obvious that I was speaking my opinion. Firstly because this is an inherently opinion-based topic just going by the subject alone, and secondly from my first sentence: "See, I find this really interesting because I completely agree with you, but your reasoning is
why I dislike 4e's monsters and prefer 5e's." I've literally described what I'm talking about as my likes and preferences. I don't think it's reasonable to complain that I'm stating my opinions as facts. That's either quoting out of context, not reading my post, or ignoring the topic.
You're missing two important differences. 1) the 4e monster's power was right there in its stat block, while the description of a spell is in another book and 2) 4e powers are mostly pretty terse and clear and can be parsed easily, while more traditional spells are less consistent and more ambiguous. So there's the extra step of looking up the spell, and the likelihood that it will take longer to resolve the spell.
Those differences become moot when you've already memorized (in the natural-language, not Vancian, sense) the available spells.
I did not find 4e's powers easy to parse. I found that you had to read very carefully to make sure you got all the effects of each ability, and you had to do it on each creature. It was particularly frustrating because all the ability descriptions look identical, but the effects are a small line of text. I distinctly recall encounters where the Artillery, Brute, and Solider of the same creature had very different rider effects for abilities that otherwise do the same thing. You may not find that confusing or complicated, but it was to me and to my play group. I remember one of our first encounters where every creature was mistakenly given the rider effect from the Artillery because that's what the DM read first and he assumed they would all be the same. I remember several times throughout play where a player would stop and say something like, "Wait, is this the one with the DOT, or the one with the push?"
And yes, when I have the spells in the PHB roughly memorized and that's one of the reason why I find that 5e is much easier. That's exactly the point I was making. I know the effects of the spells in the PHB (in both 3.x and 5e), so a spell listing is actually a useful shorthand for a large list of abilities to me. Additionally, as I said above in my response to pemerton, the DM isn't the only person at the table who knows the ability. The rest of the table can help out, since there's always a few copies of the PHB at hand and more than one player at my table (6-8 players) will probably know the spell's effects. And, again, if I want to tweak a spell list it's very easy to do since the PHB has a bunch of powers that are roughly equivalent in effect power. Furthermore, you don't have this situation where the powers of the PCs are completely distinct from those of the NPCs. I never liked the fact that what NPCs had access to was so stripped down compared to the PCs, while simultaneously several NPCs of player races had access to abilities that had no peer among the powers PCs had access to. I understand why that was -- it was impossible to do otherwise in 4e given the amount of crunch PCs had -- but it challenged my suspension of disbelief.
Again, I'm not trying to prove something deductively here. I'm stating my opinion and relating my experience and explaining the problems that we had. And
I shouldn't have to say that at all.