This has always been a consistent problem for SEGA and something I've talked about before in other threads. Outside of Sonic and a select handful of other IP like Virtua Fighter and Yakuza, they have usually had some questionable handling of IP retainment for keeping mindshare and marketshare for those IP. Sequels would either be spread way too far apart (Outrunners (1993) to Outrun 2 (2003), a 10-year gap in IP activity), be one-and-dones with no follow-ups despite having the potential (Ristar, Burning Rangers, Deep Fear, SOR4 being cancelled by SOJ and turned into Fighting Force, Eternal Champions 2 being cancelled by SOJ because they wanted VF instead), or be overall poorly managed (Sonic).
I think them being a platform holder and having all the internal conflicts between the branches is the chief reason they could not focus on prime IP during the periods they needed to. It's why Saturn went without a true Sonic game, as well. All of those problems were internal and caused by pointless internal competition and drama driven by overinflated egos. That's why there was usually not much synergy between the branches in tuning marketing for games to different markets globally (i.e VF being popular in Japan but not in US or UK, intentionally under-shipping Panzer Dragoon Saga and mocking people looking for the game in magazine adverts, etc.).
They also had problems with retaining top talent and properly promoting people in the company or putting them on projects in roles that fully suited them, again because of internal political drama. It's only after they weren't a platform holder where they've kinda gotten the message and that's why we've seen IP like Yakuza in particular be regularly retained with a consistent level of quality for multiple years over multiple generations, which is why it has a healthy fanbase. They were doing something sort of like that with VF too, but that IP is dormant and has been for several years (despite that, it's gotten more popular in Western FGC events and tournaments still are a big draw for the older games in Japan and Korea).
So while they're a bit late with the renewed focus on more proper/smarter IP management for long-dormant IP than I'd personally like, at least they're finally kind of getting the message. A lot of these are still baby steps in my eyes; they need to start buying some of these companies and making them a part of the corporate structure, that way they can retain the talent. Once they start doing that and doing some in-house sequels to some of these (no reason a SOR5 can't be on the Yakuza engine, for example, with some fine-tuning. The DotEmu guys would probably love the opportunity working on that alongside the Yakuza team and/or AM2), then I'll know they're fully on-board with the right approach.
...and they need to let Sonic Team do something that isn't Sonic. Why not a Burning Rangers remake? It's just an idea ;0
SEGA's internal conflict I felt was really blatent after Sonic became big and Tom Kalinske went full on Microsoft before Microsoft did ut with the 360/one and made some terrible decisions on not promoting their own bread and butter franchises (a famous example was charging $100 for Phantasy Star 4 because they felt it wouldn't sell and wanted to prove a point. I believe Victor Ireland said this as they wanted to put it on the SEGA CD and were turned down).
I think SEGA's mistakes have bitten them way too many times and they should have gotten rid of the top brass making these endless mistakes early on and perhaps empty out the US branch as well (Phantasy Star Universe was treated terribly by the US Staff and thankfully SEGA of America is just a Sonic promotion machine now).
ATLUS USA have essentially taken over and I am so happy they have done so as they have treated every SEGA game with as much love as their SMT/Persona/Etrian Oddysey projects and it shows!
I would love for SEGA to add Vanillaware to their family of Developers and give them a good budget to go wild on their next game. They seem suited under ATLUS/SEGA.
Oh and SEGA needs ATLUS to re-establish Career Soft again and give us more Growlanser!!!