Again those aren't their succesful franchises.
You're having a right laugh if you think the likes of Wipeout, Amped, Midtown Madness wasn't successful . Lots of XBox fans really loved the Rallisport series too, PGR but developers/publishers like to move on and do different things and so IP gets dropped for new IP. There's plenty of million plus selling IP on the PS alone that SONY dropped games like Jet Moto, Syphon Filter, Arc and so on it goes.
So its not just SEGA, but MS and SONY do it too .
You were proven wrong about the console war years where Sega won that battle and the fact they were outselling Nintendo by a large margin
. It's fact that the Super Nintendo outsold the Mega Drive, that the NES outsold the Master System only you could even try and make out otherwise. What ever way you want to cut it, Nintendo had the biggest worldwide Market share over SEGA in the 8 bit and 16 bit days. No Microsoft and Sony rely mostly on third party support with their first systems.
Sony did MS made the mistake of selling off and closing down most of its In-House studio's in the 360 era .Glad that MS knows that was a mistake that it not make again. Having strong 3rd party support at the get go is what helps one console at the start. We all know why SOJ stopped any genesis title that was associated with SOA to go on Saturn
Other than EC , SEGA Japan let Sega America make the games they saw fit . You know I highly doubt SOJ put a order in for SOA to make Bug 1 and II make the likes of Three Dirt Dwarf's never mind the shit fest that was the likes of Congo, Mr Bones, Ghen War and the like.
Funny how the SOJ MD games never got dropped and continued onto Saturn.
Sega Japan made the likes of Mickey Mouse series that was dropped , so was Ristar so was 'Wonderboy', Phantasy Star , so was Rambo , So was Streets Of Rage, So was Alex Kidd and there's plenty more and if one looks at the DC, one would see SEGA do just the same to Saturn IP . No more Panzer, Shining Force, Burning Rangers, NiGHTS, Fighters Mega Mix, Dragon Force , Deep Fear and so on it goes .
SEGA liked to move on and in a lot of cases so did the developers