While I do agree that most Worms games after Armageddon were reliant on gimmicks, Worms 2: Armageddon (AKA Reloaded) was quite solid, too
As for the rest...>WMD is a mixed bag that tries way too hard to appease everyone>The 3D Worms games are quite finicky>Not to mention that Ultimate Mayhem is missing a lot of content>Revolution feels sluggish and the water mechanic doesn't add too much to the gameplay>Clan Wars... meh>Open Warfare suffers from "handheld crunch"
And there's the spin-offs, but not only are they not retro, they're not that great, either
One version of Armageddon that I think deserves a bit more love is the N64 version. Controlling the Super Sheep is a LOT easier in it. Sadly, there's not much content in it.