3e struggled to bring in non-rpg people, especially late in its run, and 4e has failed pretty dramatically at that. The whole open playtest thing is great, but pretty clearly aimed at people who already play.
I don't agree that either edition had issues with bringing new people in.
I do think that there are unreasonable expectations in some quarters regarding the very idea of "bringing in new players".
The reality is that the great majority of the population is NEVER going to be a TTRPG player and actively working to convert them is a waste of effort. There will be potential new players ever day. Ninty percent are simply described as kids coming into the hobby. It is critical to remain focused on bringing new blood into the game. But trying to move the demographic out of the very small percentage of the overall population won't work.
If you are measuring any edition of D&D against that standard, it will look bad, but not fairly so.
(For the record, my wife is a "convert". I converted her.

I know they are out there. But she was in the percentage, she was just in the subset of that percentage that had never really been exposed to gaming. There should be a lot of effort to target those people.)
There is also the issue that the percentage is fixed, but the alternatives available constantly grow.
As to who is the target, I don't think anyone at WotC could give a straight and clear answer to that.
I think new gamers are critical.
I think 4E fans are critical.
I don't think anyone else is critical. But I don't think those two groups come close to "enough fans". "Enough fans" is critical.
So you turn to "everyone else who is a potential fan and can be gained without costing 1.01 fans in return." 3E fans are probably the easiest target. Not to say that is "easy", but they were recent fans and they left mostly over 4E. Fix those issues and you have a fair shot at getting them back.
Compare that to fans of older editions who never went to 3E or 4E. By definition that are happy with what they have and are stable in that choice. You are trying to convert a group who are defined by the fact that they haven't converted.
Of course, by that same definition, converting those fans would produce the most loyal of new fans. And I think the olive branches being held out to those groups are highly sincere.
Everyone truly is a target. And, to the extent that WotC can successfully read the group mind of gamers, there is really only one way to NOT be the target. That way is to make the price of gaining you cost more fans than it adds.