I brushed over this earlier, but wanted to mention it again and see if others here could confirm it. I took a long break from gaming from @'85 - '07, so I'm genuinely not certain. But when I did come back, I bought some of the older and newer Starter Sets, they included pregens, but did not include rules for chargen, DM guidelines for creating your own adventures (dungeon or wilderness) and much of the material we've been discussing here that we associate with the old Basic sets of the 80s.
When 4E was announced, I went back and bought the 3.5 "Dungeons & Dragons Basic Game" set (2004?), and it had minis, tiles, rulebook and pregens. IIRC, it did not contain the advanced material we are discussing. 1st Level characters only, I think.
Same with the Basic set released in 2006.
Same with the "Roleplaying Game Starter Set" for 4E released in 2008; $17, no minis, all pregen. May have included rules taking characters to 2nd Level.
The 2010 red box "Essential D&D Starter" set for 4E, did, I think, let players create characters, but I seem to recall it was extremely limited and that, for reasons I can't recall, the characters may not have been compatible with the full game (in terms of leveling up as it was presented in the PHB or the Essentials "Heroes of..." books?).
I've never seen the '91 or '94 "Easy to Master" black box sets, but I've read that it was very boardgame-y and very limited to the adventures included, unless you bought some expansion sets (or graduated to the Rules Cyclopedia). There might have been some others Basic or Starter sets in there but, like I said, I skipped ahead a few decades!
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I'm just saying that this does not seem to be an approach that is new, or at all limited to 5E. It seems that someone, somewhere a long time ago made a decision that perhaps character generation and creating custom adventures should not be part of an introductory product, and that they've been trying to find the right balance ever since.
And I'm not sure if anyone else in this thread has come out and said it, but I think it's worth floating that this 5E Starter Set simply isn't targeted at us, those who have had any recent experience with roleplaying. At the same time, it sounds like the team is talking about something external that will be available to make the product of more interest/use to us, without the risk of "hurting" the product (be that something like cost of materials, or simply including material in the game they feel complicates the product for its real market, "newbies"). It seems like a decent enough strategy and, as I hope I've illustrated above, more than what's been done in many years.