Arrogant = doesn't bother to set defences or wards against things that are unlikely to be threats.
Okay, but that still doesn't mean it's easy to sneak up on.
Large, heavy, big footprint, belches something very noticeable = Obvious and doesn't have superb senses.
The combination of the two = one of the easiest beasts in the monster manual to sneak up on. They have almost all the disadvantages of ogres combined with their arrogance. The only reason dragons should be harder to sneak up on is that if you throw a rock to distract an ogre the ogre should look in the direction the rock went. The dragon should look in the direction the rock came from. Other than that they breathe noisily, meaning they effectively have bad hearing. They are large and extremely noticeable meaning you can see them before they see you, so you know where to hide. They belch something caustic or dangerous meaning they have a bad sense of smell. They are arrogant meaning they don't directly set traps. Being easy to sneak up on is entirely in line with what a dragon is, and is one of their few weaknesses.
Now you're being exclusionary. There's clear and unambiguous precedent for D&D dragons to have keen senses. One could argue that this is one of the salient qualities of D&D dragons for some players. If someone wants to define their D&D dragons as D&D dragons have been long defined, as having keen senses, who are you, and who is 5e, to say they must change their ideas about how dragons work? Why doesn't D&D support the D&D dragons they've been playing D&D with for years already and instead replace them with big boring dire lizards?
And really, what do we gain from such a consideration during play? Oh, I guess the rogue's player gets to do the same exact tactics against the dragon that they do against every other monster in the book. How
exciting to do the same thing you've been doing. How dynamic.
Dragons with keen senses are more interesting as "big encounters" in the same way that dragons with impenetrable defenses are more interesting in the same scenario: they force the players to think laterally to overcome the challenge by neutralizing their most obvious strengths. Rogues can't sneak. Fighters can't hit. Mages can't land magic. Clerics can't heal fast enough.
Sure, dragons don't NEED to have them, necessarily. But to say that dragons SHOULDN'T have them as a rule is to fly in the face of good design and previously supported gameplay. Same with the argument that dragons should be "normal" monsters. D&D has plenty of big noisy normal dire lizards that breathe fire characters can fight as normal characters of level X. Dragons, as the vanguards for one of the game's titular threats, probably should not be big fire-breathing lizards.
If some burglar with a leather strap and a jock hits a dragon they do about d6+2 damage. The dragon has over a hundred hit points. Who the hell cares?
But a level 14 rogue isn't "Some burglar with a leather strap and a rock". He's very possibly the best sneak-thief to have ever lived. Level 10 is Master Thief in AD&D. The level 14 thief should be a better burglar than someone who can Planeshift, Greater Teleport, and Turn Invisible (all those being in the reach of a level 14 wizard). Calling a level 14 rogue "Some guy with a leather strap and a rock" isn't like calling Usain Bolt "Some guy who can run a little." It's like calling someone who can outrun Usain Bolt to the same degree Usain Bolt can outrun an average man over 100m "Some guy who can run a little".
This depends entirely on the assumed divergence from the norm of a 14th level rogue in an individual's game. 14th level might be awesome and legendary, but it might also be just-a-cut-above, or slightly-better. Superhero-genre on high-level play is not a desirable outcome for every game.
That said, I'm sympathetic the the idea that a high-level rogue is a mythic badass, but then that 14th level dragon
should also be a mythic badass, a villain every bit the equal of that rogue. In fact, to make it an interesting encounter, that dragon should probably be the BETTER of that rogue, so that there is an uphill struggle. Death-by-two-rocks-and-a-hunk-of-metal while flailing mostly ineffectually is not a fight worthy of being called a "dragon-slaying" in my book. It's not a fight worthy of the awesome of that titular threat.
Good job we're talking about a bloody big firebreathing lizard and not a ghost then. Dragons don't have "impenetrable defences". They don't need them. They are just strong, tough, smart, and mean.
The crux of my counter-point here is just to illustrate that your version of what a dragon is isn't necessarily the version that D&D has most famously supported, nor are they the most interesting to play with for a game that is named after them, so to state not just that they should be like this, or that they are like this in your game, but simply that
this is what they are, period seems to vastly under-consider the ideas of other people who play the game. This is a game that includes pyrohydras, dragonets, dragonnes, and chimeras. It includes half-dragons and fire lizards. It includes dire lizards and animentals. Dragons should be more than a normal monster, I think.
Not that they can't also be a normal monster, too. Just that saying that they
are already this, without caveat, is ignoring vast swaths of D&D history, the nature of the dragon as a brand tool for the game, the diversity of the D&D monster milieu, and what could possibly be a lot more fun than a fight "just like every other monster."
RangerWickett said:
Did St. George have a magic sword when he slew his dragon? No, he poked it with a lance and then leashed it with a lady's girdle.
Did Hercules need a magic sword to chop heads off a hydra? (Big magic lizard in most mythology is as good as a dragon.) He just used some old sword and a plain torch.
Dude, did you honestly just argue that a dude with
SAINT as a title, and the
CHILD OF A GOD are low-magic paragons of badass normal?
I mean, if you like a mythic game of saints and godlings, more power to you, but lets not imagine that these are creatures who are non-magical. They exist at the very APEX of magical thinking.