There's a good post about opponent bots over at Gaming Verdict.
This is one of those industry changes that has slipped under the radar, I think. My friends and I used to spend a ridiculous amount of time playing with bots in Perfect Dark on the N64. Super Smash Bros. is another great example. I'm always disappointed when games that could include bots don't.
Gaming Verdict mentions the steep learning curve of gaming against human opponents. Just the other day, I was introducing a friend to Call of Duty 4 multiplayer; the game didn't take. He told me that it definitely seemed awesome, but someone like him, for whom games are only occasional recreation and whose reflexes are no longer lightning-quick, simply can't compete. And competing split-screen, just me versus him, is nothing like the gleeful chaos of our Perfect Dark experience.
All games have that problem with competition... not just FPS fragfests that require split-second reactions. I'm a fervent and lifelong gamer, but even I don't try to compete online with my favorite RTS game, Battle for Middle Earth 2. The several family members and friends with whom I've played that game prefer to team up against bots in skirmishes or campaigns.
Michael de Plater, the creative director of Tom Clancy's Endwar, has cited that upcoming game's use of voice commands as a way to counteract the advantage of knowing macros and complex controls, but difficulty of control isn't half the problem (in fairness, de Plater doesn't suggest that it is). Most competitive online gaming networks feel as if professional, college, and high school sports conferences were combined into one. More than a few factors separate the amateur from the professional.
CoD4 admirably matches pros with amateurs in team matches, but I think the amateurs more often feel more useless and outmatched than like they're contributing to the team. That's how my friend felt. That's how I feel sometimes... especially when another player clearly knows the map, and I don't. The greatest sense of accomplishment comes from winning; nearly losing, but winning. Losing occasionally or even half the time is no problem. Losing almost every time is not fun for most people (unless it's to a pretty lady, of course). Relatively few have the personality type that views nine losses as an acceptable price for one win, when he or she is only competing for entertainment. One can view his or her own mild contributions as meaningful contributions, but that is, perhaps, not an automatic or particularly common view.
The skill levels and playstyles of players are hard to quantify, so matchmaking systems only help so much. In fact, matchmaking is downright useless when players alternate between play-options. A player might be good with some weapons/units, but not others; with some factions, but not with others; on some maps or scenarios/modes, but not others. And suppose I've improved my skills in single-player mode since the last time I played multiplayer. Should I now have to begin facing easy human opponents, because I haven't yet proven myself to matchmaking system?
Furthermore, a person's playstyle and desired degree of investment in the game can change from session to session. A gamer can feel particularly competitive one day and be interested in only leisurely engagement the next (perhaps due to being tired after a long day's work).
Remember that the difference between a professional and amateur isn't just skill and experience, but interest. A lot of people play casual club sports -- not because they're not capable of more intense performance -- because they prefer a different pace, different style and rules, or do not consider the game a high priority.
Finally, though I'm generally a big fan of reducing predictability in games, bots can actually offer a deeper sense of strategy than human opponents precisely because they're more predictable. Half of battle strategy is anticipating your opponent's next move. When you're playing against hundreds or thousands, if not millions, of other human beings, then you rarely face the same opponent more than once or twice. As a result, you can only learn and adjust to the broad strategies that are common among players, and not the specific strategies of individuals.
Online multiplayer games are more tactical than strategic... the player must react to momentary events, rather than plan for organized movements. Bots (particularly, campaigns against bots) enable true strategy.
Another thing I had to explain to my friend about CoD4 multiplayer was why one of his matches was ended abruptly when "the host... left the game". Sure, there are plenty of inconsiderate players who cut a game off just because they didn't like the map or the way the match was going, but there are also players answering telephones or doors, being distracted by kids or pets, or having to unexpectedly end their play-sessions.
As Gaming Verdict points out, the ability to pause is easier with bot-driven games. Games could even be designed to automatically replace a player's character with a bot if that player has to leave the game temporarily. Life is unpredictable. A purely logical software program is more likely to understand that than a stranger.
I realize that developing fun and competitive AI is no quick or easy task. But remember that even simple AI can be fun when combined with the right dynamics (ex: Turok shows that even a dinosaur that simply runs straight for you is tough when there's also a soldier nearby shooting at you).
We miss our bots. Give them back.