It does increase the filesize, but everything does. Look on the bright side though; Wc3:WoW will be ten times smaller in file size than the actual World of WarCraft is. The original WoW was - I think - 5 gigabytes. Now it's 14 gigabytes. Wc3:WoW will probably hardly even reach a gig, if it even gets that close. Besides... it's all for the better to make the atmosphere of the mod much more like World of WarCraft.