i think at this point it would be more surprising if sega released an actually good sonic game
quite frankly, i dont think two of those even belong on a list of disappointments because after the first major flop everyone should have significantly lowered their expectations.
personally I feel that people expect way too much of a sonic game and then get really critical when they come out
because sega does that thing where they release two meh games but then a really good one or two
like sonic rush was good, then sonic '06 came out, and sonic colors/generations was good, but then rise of lyric came out
sure '06 wasn't that great, but lyric wasn't terrible in any objective aspect