I seem to remember IGA striking certain Castlevania games from the record and deeming them "unofficial" titles because they didn't match up with his clusterf**** mess of storyline he attempted to conjure up.
I assume you're talking about CV64, LoD, & Legends; the formers being re-added as "Gaiden" stories. Legends was omitted because it conflicts with CVIII no matter what anyone says. All he did was try to piece together the games in a cohesive timeline, that if one did their homework instead of brushing it off, actually makes sense given the long history of the franchise. It's not as complicated as people make it out to be. My waifuu Nagumo can explain it all in a topic that would make sense to everybody, if she feels like doing it.
IGA turned Castlevania into a predictable, mundane series. He did a few good things. But his run should have ended with Curse of Darkness. It's because of him that Castlevania has shameful titles like "Judgement" in it's roster. I cringed when I had to buy that game. The only reason I bought it is because I own everything Castlevania (and I mean everything).
Predictable? Mundane? Hah! Most of his games were enjoyable with only a niche group of disgruntled fans hating them (this argument reminds me of those people that hate on a movie franchise, lets say X-Men for argument's sake ((a franchise that's
continuously hated on across internet forums for various reasons)), yet still go watch the movies be it paying for tickets or otherwise, only to bitch about them on the 'net, then re-watch them at a later point for whatever reason and most likely watch the sequel(s) all the while STILL proclaiming they're "complete garbage.") All of his games have nods and homages to past titles created before him, and I respect that. Even
shitty"less-than-stellar" games like Judgment still have their redeeming qualities.
And, take it from me,
you don't own everything. 
He did a good job with SOTN, LOI, and DOS. The rest could have all been skipped, as all they did was the same thing as these other games, only worse. If you want to talk about a developer who should have another go with Castlevania then why not mention Treasure? They made one Castlevania game, Super CV4. And it is one of the greatest games of all time.
Super CV4, while excellent, has it's flaws just as much as any other CV game, so I respectfully disagree with saying it's one of the greatest games of all time. Treasure doesn't exist anymore [to my knowledge], I'm pretty sure the team disbanded or got absorbed into other developers.
I can't believe, in the year 2013, people still can hold grudges and so much hatred for this man. I remember reading "IGA SUX" articles way back in 2004, he was being insulted left and right, even to the point where people were convinced he was
sexist. Say what you want about his storytelling techniques, but in my opinion, the good he's done for Castlevania outshines the bad, and he was a wonderful asset to the series. And I firmly believe a team-up of IGA, WayForward & Yamane would yield excellent results.