I actually haven't seen any reviews of the recent games that say anything about the old Dreamcast titles, to be honest.
Every review which generalizes 3D Sonic indirectly does so. Further, I've seen some go so far as to label STH3 as the "beginning of the end" back when it was re-released on Virtual Console, which is completely nonsensical considering that if you ask ANYONE their favorite 2D Sonic game, one of the 3 possible answers you will get is S3&K (STH2 and SCD being the others).
Further, I have read today, Sonic Colors multiplayer previews that claim Sonic co-op was only done properly in STH2. Explain to me the logic behind that one.
Your level design comments on Black Knight and Rush leave me to believe that you're gauging them based on the early game. Black Knight has ludicrously straightforward levels to start but gets more platforming-involved as you progress, with several stages making heavy use of stunts and well-timed jump cancels to fly over hazards (which are CONSIDERABLY more visible than Secret Rings' obstacles). The level-up system is a lot better conceived in BK as well, considering you will not be penalized based on control sensitivity preferences that range all the way from molasses to practically teleporting to the opposite side of the screen, nor will you ever need to re-check your upgrade list to disable features that interfere with your current mission objective (who the HELL thought of avoiding spheres?). Speaking of which, Secret Rings can be very hit-or-miss in its mission objectives in general. Black Knight is a lot more solid in that regard, although the "avoid townspeople" ones could DEFINITELY stand a longer draw distance. Thankfully they're rare.
Rush, meanwhile, over-uses bottomless pits in its middle-to-late-game, which is not a good thing to do when you're moving so fast as to barely see in front of you. It's especially frustrating with Blaze since she tackles the levels in her own order, while Sonic's order is the obvious intent so far as difficulty curve. Rush Adventure is considerably better in level design, although the material/ship stuff may be seen as distracting. Both Rush games fail in final battle scenarios. That's the one thing the console games have largely done better. By all means, they're good games, but Sonic can be better.
And don't put all of the journalists on the same bowl. Tons of them have very good reviews.
Naturally the quality of any trade varies with the worker. I can't speak for anyone else reading this, but for me, you're stating the obvious.
With Sonic, though, the fragmentation in the fanbase (as I always say, there is no consensus on what a "good" Sonic game should be) gives the reviewers an exceedingly difficult job. Their analogies to Sonic's history tend to be very narrow-minded and thus clash with a good deal of the fans, as every SA2 lover feels every time someone is stupid enough to claim that 3D Sonic was never done well. While only a fool would say that ALL reviews are untrustworthy, I believe that the majority of them are. It's not even just Sonic; several other fandoms have led me to articles that can only possibly be excused as sheer ignorance. I've seen everything from the inability to locate the Options menu to criticizing control setups that don't even exist (I still need IGN's Daemon Hatfield to explain to me where the "right analogue stick" is on a remote/nunchuck-only Wii game).