A lot of fans like the idea of revisiting things or characters they found particularly exciting. They can have this notion that if we revisit those things it will be exciting again. But context is everything. Part or the original excitement was the novelty which you no longer have in a revisit. So revisiting a favoured character will only be interesting if there is something genuinely fresh to bring to the game and it's justified by the larger story. Otherwise it's just meaningless pandering.
TNG began the era of connect-the-dots that continued through the following series. And connect-the-dots is something that's been going on in Trek lit since the beginning. But candidly it's rare that this practice really works and it's usually just more pandering. It also makes the fictional universe seem that much smaller every time it's done. It isn't necessary for everyone to know everyone else and for everyone to be privy to everyone else's experiences.
Please, let's keep it to a minmum.
Truthfully as much as I like Star Trek Continues
and the character Elise McKennah I am somewhat disappointed seeing the idea of her character in the TOS era. It's so obviously a connect-the-dots to the TNG era in the face of no evidence that ships' counselors existed in the TOS-TMP-TWOK era. We also don't see evidence of it in the Enterprise C era (although they could have been there). There's supposed to be about a century between the TOS and TNG eras so why the insistence to introduce a Counselor now? It's simply a connect-the-dots move.
The idea of the proto-holodeck is more iffy because GR did have the idea back in the day and it did appear in TAS. But for a lot of folks not knowing those things it is a connect-the-dots move. I don't really mind it, but they could have done without it.
What's being done in Phase II
is also a connect-the-dots move and one (in my opinion) which doesn't make sense in the "real" world of TOS. Why would Starfleet drastically refit a ship only three years into its five-year voyage and then refit it again (even more drastically) a few years later just prior to TMP? That strikes me as a lot of unnecessary effort and downtime. But the Phase II
folks feel compelled to cement this connection between TOS and TMP to rationalize the visual differences between TOS and TMP. It's an indulgence that in the larger scheme of things---telling compelling stories---doesn't accomplish anything. It's just "because."
TAS did it with Robert April. In a more real world perspective it isn't necessary for Kirk and crew to have ever even met Robert April. Certainly the story he appeared in could have easily been told without him. But the writers wanted to indulge in connect-the-dots. It didn't add anything to the story even as it didn't really take away anything from it either. It's a touch of fanwank and in that instance it did no harm. But I certainly wouldn't want to see this all the time.
Of course, that's just my opinion.