Standing wristlocks, no. Wristlocks on the ground, occasionally.
It has little or nothing to do with the gloves. MMA/Vale Tudo matches were fought bare-knuckle for years before the modern MMA glove was developed. Even with the gloves, you can still apply a wristlock - the extra wrist support is not that significant.
The reason has to do with the context in which standing wristlocks work. They are largely the grappling equivalent of a sucker punch - something you can slap onto an adversary who is posturing, trash-talking, and shoving but doesn't expect the fight to be all the way started yet. Just as a sucker punch is an effective way for a bar fighter to take down a victim who doesn't realize he is in a fight, so a wristlock can be an effective way for a bouncer/corrections officer/police officer to gain control of a belligerent subject who is threatening to start a fight but hasn't started swinging yet. Once the punches start flying in a one-on-one fight with a competent opponent, you've pretty much missed your opportunity. It's too hard to gain control of the wrist and if you do get hold of it, it is too easy for your opponent to yank it back out of danger. Obviously in MMA competition both fighters know from the start that they are in a fight, so there is no opportunity for this sort of surprise attack.
Wristlocks on the ground are a bit more practical, since you can more effectively control your adversary's movement and isolate a limb.
There are other contexts where standing wristlocks can be effective, but they don't apply to MMA competition.
I have a friend who works in a detention center for juvenile delinquents. When faced with a violent kid, a team will work together to pin the subject against a wall, where one staff member can apply a gooseneck wristlock as a come-along in order to walk the offender to his cell.
In the samurai era in Japan, an surprise attack might start with the assailant grabbing the victim's wrist to prevent him from drawing his sword. Meanwhile the attacker could get his own sword out first. This is the origin of the classic aikido "grab my wrist" defenses. In this case the wrist lock makes sense - if your opponent hangs on, you can complete the wristlock, if he lets go, you get to draw your sword. I've seen the same principle applied to modern gun retention tactics.
Standing wristlocks are a valid technique and they have their place, but you are very unlikely to see them work in the middle of an all-out one-on-one fight with punches being thrown.
