Sega did
plenty longform games from very early on (though many weren't localized due to failing sales/platforms). On Saturn there's Deep Fear, Shining the Holy Ark, Magic Knight Rayearth, two Mystaria/Blazing Heroes/Riglord Saga, Burning Rangers, three Shining Force (III) games, two Dragon Force games, The Legend of Oasis, two Sakura Wars games, Panzer Dragoon Saga, Shining Wisdom and more, as well as games that bridged the gap from arcade to home like Panzer Dragoon and NiGHTS (having a story etc. despite arcadey gameplay). They continued on Dreamcast with Shenmue (which started life as a Saturn project of course so even with that they were pioneering in the cinematic approach early on), Headhunter, Skies of Arcadia, Rent A Hero, Hundred Swords, three Aero Dancing/Wings, two Sonic Adventures, Metropolis Street Racer, Jet Set Radio, Phantasy Star Online, two more Sakura Wars etc. Plus their sports games, you may call them arcade style but sports built empires like EA's at home and they did very well with their own output quality wise (and clearly differ from arcade sports, though both Sega Rally 2 and Virtua Tennis 2 had meaty content added too).
Of course it didn't work out but that's like going to someone and asking to
just make a video go viral, lol, it's not for lack of trying and it's not just quality that dictated sales/success, especially when making games for platforms the writing was soon on the wall for their future thanks to external as well as internal factors and just falling back to a sales discussion adds nothing, we know they didn't succeed, this thread only exists because they didn't. They had more in the pipeline that ended up on Xbox and elsewhere like Gunvalkyrie. Their later longform stuff as a 3rd party build on what came before, from Yakuza to Valkyria Chronicles or whatever. Some like Phantasy Star, Beyond Oasis and Shining Force (and others that didn't get to continue on like Golden Axe Warrior, Zillion or Sword of Vermilion) were done
before the Saturn or even the Genesis so,
they were quick, not slow 
That's another argument altogether about transitioning series from 2D to 3D (action based I guess, not like Fire Emblem which remains largely the same with 3D graphics like Shining Force itself transitioned earlier), not from arcade to home. I guess they don't have any still relevant major 1:1 examples (as Phantasy Star Online may as well have been a new IP compared to past games, though 3D Sonic itself became fairly successful and you can easily connect the dots between shmups, sprite scaling rail shooters and full 3D like Panzer Dragoon which had its moment in - cult hit - history with the Saturn and Xbox entries as their racing and sports games went through a similar process) but they were obviously among the major pioneers of 3D gaming with all new rather than previously 2D games, you can't be serious, they were leading in 2D, 3D and online. For 3D they obviously moved the industry forward with their racing, fighting, lightgun (which Namco followed after for their own arcade and PS hits) & online games, hell, they went full 3D JRPG before Square on both Saturn and the DC and even Shenmue paved the way, though yes, it didn't work for them, we know, lol.