Pikes and to a lesser extent longspears are huge force multipliers if there's actual teamwork. Sticking with a big blob of inf is where pikers can really shine, poking in and out of the front lines from a place of relative safety and watching flanks for cav charges. Defending ranged from cav harassment is also useful beyond what is reflected on the scoreboard. If you are doing 1 v 1 as a piker, you (or more likely your team) failed at basic teamwork somewhere along the way, or your team lost and you are one of the survivors being hunted down. There's too many melee inf who don't seem to get how useful pikers are as support and will let them fight on their own. If you and a piker are fighting vs 5 guys at once, your priority should still be to attack/distract anyone messing with the piker and trying to give him openings to stab. A good piker can deal with a lot of enemies at once using the the tricks Sandersson mentions above, but it's still not an ideal situation and much harder to deal with than if you had another type of melee weap.
