I prefer Frontiers & Shadow Generation scripts over Lost World & Forces and whatnot, but it is kinda true that Ian works better when fleshing out Sonic Team's script over creating stories. It worked for Archie Sonic, but Game Sonic does feel little off in IDW vs games directly, even with Evan too. It is jarring how IDW just avoided Shadow while Sonic Team made him go beat Metal Overlord lol
There are the other nuanced things that Ian does that arent great, too many references, some characters etc. but ngl removing Ian might make game scripts worse, so Id stick with current methods for now. Tho IDW will probably never go beyond average unless writing team evolves, which is unfortunate.