Nintendo

Makes sense to port them in this case. More than in most series with an overarching story, lots of context in later Ace Attorney games is missed if you haven't played the earlier games. It's not to Kingdom Hearts level (the above only really applies to the main entries, you don't need to play Investigations or GAA), but still more than most.

While I try not to delve too deeply into marketing speak, I think they are only porting all the games because they are selling well, and if they are selling well enough, new entries would surely follow.

Capcom is doing well for Resident Evil, by both remaking older inaccessible games and creating new ones, hopefully they will do the same with Ace Attorney and their other franchises too.

sometimes? he's not always involved, but he sometimes is

To me, voice acting can be a mixed bag. It can make a game much better, but can also make it much worse. The big issue is pacing and delivery - I can read the discussions about exactly how the victim fell down really quickly, but with VA that becomes a laborious affair.

It also isn’t great for writer adjustment. If a game has late changes to one piece of evidence presentation dialog, they may cancel it if it’s unfeasible to re-record the lines given by the VA.

The Great Ace Attorney Chronicles had VA for certain key scenes, and it worked out pretty well, but ultimately you should expect these games to be very text-based.