4b. I don't miss bots, but I do really miss more co-op options and the idea that you don't have to be an expert to play a given game online. =\
Well, I certainly miss the days when it was considered standard to have an offline multiplayer mode with computer bots if you didn't want to deal with human opponents. I think Killzone 3 is the last game I can think of in a long time that had that option (and even that's not as robust as what Perfect Dark did), as even Black Ops requires that you be online to play against bots.
As for the need for more Co-op, though, I certainly agree. My experience playing through the Portal 2 Co-op campaign was pretty awesome, and I really enjoyed the Co-op online multiplayer levels in Uncharted 2 a few years back. Sadly, Naughty Dog didn't feel the same way and only really supported competitive multiplayer. And I really dislike what Perk systems have done to multiplayer. Sure, if you have a decent matchmaking system, you should always be paired up with players of your skill level.
However, I've seen several multiplayer games that just lump everyone together, allowing the veterans to just making multi inaccessible to anyone not willing to grind for 5 hours memorizing maps and slowly obtaining Perks. And what if you want to play multiplayer and there are no players of your skill level around to match-up with? You either don't get to play
anything or you get lumped in with the veterans as fresh meat. Bleh. Players who are already good at the game shouldn't be given ways to kill everyone
even easier.
As for Game Length, I agree that a game should only be as long as its content can support. However, IMO if your main game can't support an experience that fits the price you're charging in the eyes of the fans, you need to either have supplementary game modes to fill in the gaps or something about the content that changes to encourage replay value (GoldenEye, Perfect Dark, and Timesplitters 2 were masters of this). It really troubles me seeing so many games you can easily finish and pretty much see everything there is to see in 5 or so hours with no incentive to play any more of it.