Yes, we do.
3.8 was the last release by the actual vBulletin people. Everything since then has come from a new group that was brought in after vBulletin was bought out and the original people left.
3.8 is also extremely stable and completely patched up, whereas 4.x is still buggy and full of holes.
Also, there are TONS of plugins and such for 3.8 but not that many for 4.x. Since 4.x was an almost total rewrite of the code, most of the plugins that are for 3.8 will not work with 4.x.
Every update for 4.x breaks the skins (ALL the skins for EVERYONE), requiring constant maintenance in that area. Why? Because idiots at the current vB screw with the code that handles the skins in every update...because they wrote it willy-nilly into and through everything else. Baez could tell you all about how retarded it is.