Bayonetta and Vanquish are still older games even if they aren't Genesis era old. I'd also argue that they are much more relevant franchises in 2017 than just about anything they could bring back from the Genesis era. I obviously like games more than the average person does but I wouldn't recognize any of the games you mentioned if I saw someone playing them. I've heard about Phantasy Star and Streets of Rage lots of times but I wouldn't recognize them myself. I don't think I've ever even heard of ESWAT. I googled it thinking that was an acronym for something but that is its actual title.
I think it's more of a case of Sega looking at easier ways to make money, which isn't really a bad thing. For a lot of people, news of a new Shinobi or Alex Kidd or Golden Axe would be of interest to them. New games can be set up in these dormant franchises, which makes them appealing to old fans as well as can create new fans by opening up a new series to them. You may have only heard of Streets of Rage, but back in the day, it was Sega's exclusive beat'em'up game, and was basically their answer to Final Fight. And Shinobi is basically their version of Ninja Gaiden, or rather the opposite should be said considering Shinobi came first. Point being, Sega is sitting on a trove of underutilized IPs that many players know of and have fond memories of, so rather than just let them sit dormant, they may as well be used. As we saw with the most recent Prey, existing IPs are easier to sell than new ones, so rather than Sega having to take constant risks with brand new IPs they can just dust off some old ones and make new stuff for them, assuming though they don't do like what Prey did and do something 99% different than what the IP was originally based off of.
I hope more companies follow suit with this. I'd love to see some of these old franchises I grew up with getting new games.
