1) The use of the cookie cutter idea isn't original, since someone invented the cookie cutter. (unless you invent a new way to cut cookies, you are unoriginal) (at the same time, cookies are unoriginal period) (so is the use of flour in foods...) (then again, the idea of food is unoriginal) where does it end? it ends at the point where StarCraft maps are "unoriginal." technically the only original person was the 1st person to make a map, which are the programmers who made the SC campaign. Everything is relative to your own opinions on originality, and exactly what frame of perspective you are looking at.
2) No one has yet suggested the mutation/splicing/combining of 2 cookies. Combine a snickerdoodle and a chocolate chip cookie and you get something new. (combine some maps, and see what you get. ie: custom hero + mass attack game = footmen frenzy [which has been done {and failed since it-over- was lazy}]) (or my idea, Custom Battlefield, a combination of AoS maps, and the custom spells/heroes of CHW [which is looking very original, and is in progress])
3) If you want to really make a good, new map, use EUD's. Its very likely that blizzard will not patch SC anymore. Making a map (any map, AoS, mass, RPG, micro, random, etc.) with EUD's can really change the game. For example, in WC3, many maps have different text commands. Typing ",Help" will start a tutorial; or typing ",1" gives a description of spell #1 (in DBZ maps, typing "SST" activates super sayen trunks). Or add some click detection, or key stroke detection (the number pad WASD idea is good and original, with some minor kinks).
4) EUD's + text can make a map massive. Get. Over. It. If the map is
good enough, people will dl it online, or just wait a long time to dl it. ("long" time is relative to the player's sense of time). (ie: norm map used to take a long time to DL, since he didn't compress the alpha, but people still waited a long while to dl it, and for others to dl it so they could play.)
None.