If we want opinions of a mesh tool then I would say its fairly pointless. You can emulate the effects obtainable with colour/transparent overlays to build up the effect your after which are more flexible and easier to edit in the long run. In saying this I might be missing some esoteric function of a mesh tool but as far as complex fills are concerned Xara can already do it without yet another tool being added for the sake of it.
As has already been said adding it wouldn't be that difficult, Drawplus8 already has it, rather pointlessly, so if it were important enough I think it would have been there a while ago.
Derek