Alright, lets begin with shortening the arguments shall we?
Multiplayer: For this team, the argument is that theres tons of replay-value here, whereas Single-player replay-value tends to nosedive rather rapidly for them, theres more challenge, more fun in Multiplayer for this side
Single-player: IN THIS corner however the exact opposite is stated, many single-player gamers dislike Multiplayer, many of my friends i've talked to either love or hate (I rest in the middle but more on that in a minute) Multiplayer and prefer a game that advertises a solid single-player and/or co-operative single-player campaign to actually hold it's water in both department.
My argument: Alright (cracks his knuckles) lets begin, Right off the bat let me state that I love both single and multiplayer games TO A POINT,I played Medal of honor Spearhead (PC shooter) until the CD literally wouldnt run anymore online, I loved Halo Multiplayer, I loved COD: Modern Warfare 1 Multiplayer, and I even occasionally get on MAG (a PS3 MMO Shooter with RPG elements) still multiplayer wise. HOWEVER I prefer single-player more often than not.3/5s of my console and PC games are mostly for the singleplayer content. Now Midgeamoo's argument is that a game thats mostly multiplayer focused with a shoddy singleplayer content should advertise that it's singleplayer is indeed shit, now while I would appreciate such honesty from a gaming company I'll probably sooner see hell freeze over.
Several other members in the forum stated that if A games going to focus all efforts on one section why bother with the other? I agree with this, Lets look at each side of this argument, Oblivion and Morrowind, both games of the Elderscrolls genre, were considerd incredible in-depth strategy games with a absolutely massive modification community for both, Now lets take a look at Red Orchestra and Team fortress 2, Both of these games are equally popular in the gaming community, however both are (almost, with exception to RO's "practice" setting which pits you against AI players) Strictly Multiplayer based only, with rabid fans as far as the eye can see.
Now with both of these in mind, lets do a recap of what I've stated, Both are exclusive to either Multiplayer or Singleplayer, both have legions of die-hard fans, lets look in why I think each of these arguments both side's arguments have merit and have flaws shall we?
Multiplayer: Now the argument here is that Singleplayer tends to be incredibly boring for these players. Fair enough now lets look at a match of Team deathmatch or capture the flag on your typical shooter Multiplayer shall we?......huh....every players doing roughly the same thing as in singleplayer only on (typically) smaller or the same maps with even LESS things to do or going on. HOWEVER there will always be a challenge here as few players (outside of MP clans who train to play with similar strategies) play alike. Everyone thinks differently and so such interactions can last longer; HOWEVER just as another person stated earlier, eventually Multiplayer will lose it's rush, just as with....say Halo 2 for instance. Fewer and fewer people will play, until finally the servers are shut down and the multiplayers gone. Your XX dollars you spent for this game are now null and void, all those weeks/months/years you spent getting skilled at this game are now null and void as you cant play anything save local matches against the same people until even that becomes too repetitive.
Singleplayer: Alright, the field i'm a little more familiar with. Time to get cracking, the first argument for SP games is that many games are drifting away from singleplayer focus to focus on multiplayer games. This is true, the Call of Duty and Halo series (both revolutionary shooters from their singleplayer AND multiplayer content) were both incredibly popular in both aspects (although at the time Multiplayer was just getting it's momentum) However many multiplayer gamers consider Singleplayer games to be too repetitive. And sometimes I admittedly agree, after the 2nd or 3rd playthrough, most singleplayer games (short of Open End RPGs such as Fallout or Elderscrolls) have lost their value to me, HOWEVER. When a developer completely drops the ball on singleplayer (making it ridiculously generic or your just going through the motions about as much as you would in a Kung-fu dojo learning muscle-memory) then you've wasted your staff's time and the customer's time by producing absolute shit thats going to turn them away from wanting to risk buying a sequel (I know many of my buddies, as I said, both multiplayer and singleplayer gamers. Didnt bother buying Gears of war 3 if they were doing so for the campaign because the second game felt like the first one with a new voice-acting script save the worm scene).
The solution here: There is no clear-cut solution, the best we can do is do a few shots, agree to disagree that each side doesnt like the other's preference and deal with it, I'd love nothing more than to see rights for singleplayer-only/multiplayer-only/both purchases and have companies take the time to polish both out well. But as I also stated earlier we'll probably sooner see hell freeze over than game developers/publishers focus on the attentions of both equally and make a fine job of it.
TLDR; (well there goes an hour and a half of my life, hope your happy) Long story short, nut up or shut up, this is an argument thats going to drag on just as long as Communism vrs capitalism or Atheism versus religion etc. with either side whining the others wrong until one side keels over dead.
PS: I've been drinking quite a bit tonight so if my punctuation or spellings wrong I apologize, I'll try to make a mental note to fix any errors tommorrow if I can