Greetings!
Hey there Green Knight!

I would also say that even though cohorts get a share of the experience points, they are worth it in the long run. The recruitment of cohorts provides, as I demonstrated, not only additional "firepower" as it were, but also increased operational flexibility. Bringing along well-equipped followers also enhances these abilities. The group not only has additional options for combat operations, but the group's scouting abilities are enhanced, so that when the group learns about the enemy's whereabouts, the main group can set up to hit them really hard! Furthermore, the group actually has some competent people who can run errands, guard prisoners and extra gear and pack animals, as well as taking care of numerous smaller but still important missions.
Beyond all of these benefits, of course, when the group must assault the huge undead temple filled with vampires and Death Knights, should the group succeed, it seems to me far more plausible for the group to do so while attacking with a reasonably strong force of fifty or so instead of merely four people. For me, having a party of four heroes waltz into some evil fortress and slaughter everyone and win the day just seems to stretch credibility--if the DM is playing the opposition with intelligence and skill. For example, in my own campaigns, when the group prepares to assault some huge fortress or something, and the opposition is high-level, well-organized, and skilled, there is just no way that a group of four heroes are going to have much of a chance. The assumption within the game is that everything will go the player's way. Even allowing for various exigencies of combat, it seems to detract from the heroism and accomplishment if the party succeeds because I, as the DM, pulled punches for the opposition. However, if the party brings their cohorts and followers, though I can expect that the group will do their level best to ruthlessly defeat the enemy, I can rest easy that I can operate the opposition at full strength, and let the chips fall where they may, you know? In such a situation, though the group will suffer casualties, I know that even with the opposition going full-bore, that the group has a reasonable and plausible chance at achieving victory.
When the smoke of battle clears, and the screams of the dying have subsided, the players can be confident that they just succeeded in a great battle against the Forces of Darkness!
I should also note, too, that recruiting cohorts and followers requires not only more gold and effort on your character's part, but that these relationships will also make other social and economic demands upon the character. If the character desires to have an elite force of fanatically loyal cohorts and followers, then the character should be prepared to put in the time, gold, and energy into forming and strengthening such valuable friendships.
Of course, when the player engages in such, these kinds of developments also open up new roleplaying opportunities for everyone involved, and it also increases the plot development and scope of scenarios that the DM can design, for the DM has numerous new characters and different complex relationships in which to deal with.
Semper Fidelis,
SHARK