I'd guess it's probably more about competing with other brands by releasing new products. if they stuck with the same products it might not capture that latent demand from the part of the market that likes to have the latest, newest, most improved versions even if the old version was fine; or the inevitable part of the market that didn't like the current version for whatever reason.
I had the red 265 and rated it the best fell shoe I'd ever had except for the durability issue with the upper, which is what the blue model supposedly improves on. the grip was excellent - far better than old grey and yellow mudclaw 333 and any roclites. I've never tried x-talon though. (next I'm trying walsh pb racer for the first time.)