I haven't owned a desktop in forever and laptop+wifi game all the time...can hardly remember the last time my wifi signal was dropped. Bottom line is if you are getting disconnected from a game over WIFI these days its because...
a) You have a crappy router, go buy a decent one and it doesnt even have to be more than $40-50
b) You don't have the router configured properly...blocked ports or interference from broadcast channel
c) Your ISP sucks and they are dropping your connection. This would still effect a wired connection.
d) You live in a bunker where all your walls are reinforced concrete or a mansion where the router is 100' from your computer.
For a MMO game, wired over WIFI has no benifit. For a FPS where milliseconds in reaction time can mean life or death, then yes wired is usually beneficial. If you want a gaming laptop because you like to play on the couch or when you travel then get it for those reasons... don't scare away because of a few ms of wifi lag.