I've been playing for almost three years and now, as I'm starting to pay attention to the details in my playing and comparing it to other guitarists, I noticed my wrist position in the lower strings is really curved and it damages my wrist, I've only had only one electric guitar, an Ibanez S521, this started when I was practicing some arpeggios on the low E string between the 12th and 16th fret, when I played in the 5th string my wrist was straight in a natural way but in the 6th string when I reach from the 12th to the 16th my wrist bends completely. Could this be that my neck is not suited for my necessities? Forgot to mention, my hands are fairly big related to the average person. Edit: I can play with the wrist fairly straight with the neck pointing at a ridiculous angle upwards
J.P., There are some unknowns here. As Tim implied, where you have the guitar strapped on (up high on the belly, or down low like a rock star) makes a huge difference in your playing comfort.
Or are you playing strictly sitting down? An armless chair or stool is best. The WORST scenario is when a player is attempting to phrase chords and arpeggios whilst slumped back on couch cushions, or laying back on a bed, supported by pillows. (Your arms/elbows are trapped, and your arms are not free to move and adjust comfortably, and your wrists become strained.)
If you have fairly large hands, my instinct is to tell you, "No, your guitar's neck is not too thick".
The issue with your wrist may be due to how you are sitting or standing when you play. If you need to contort your wrist to reach the lower strings try using a strap, even when you sit, and placing the guitar body in front of your body. Many electric guitarists sit with the guitar on their right leg which causes a contorted left hand in some cases. Your statement "I can play with the wrist fairly straight with the neck pointing at a ridiculous angle upwards" is quite unfair, and a little prejudiced. You have essentially solved your own problem. As for the angle being "ridiculous" some guitarists play with the neck almost vertical, like a cello or upright bass. As for the neck being too thick, people play the same arpeggio patterns on the classical and that type of neck is thicker than any electric guitar I've played. Change your posture and keep the neck at whatever angle is required to relieve the stress on your wrist.
If your guitar is an Ibanez S-Series, and you have large hands, the answer to the headline question is almost certainly "no, the neck is not too thick". If anything, it might be too thin - the necks of these guitars are as slim as they come, and a thicker neck might offer a better angle for your thumb to rest on. Could you borrow something with a heftier neck (a Les Paul or LP copy, for example) from a friend and try if you feel more comfortable with it?
Have you consulted with an experienced guitarist (your teacher, if you have one) and asked if they consider your hand position problematic?
Also, you write that this damages your wrist - are you actually feeling pain or stress in your wrist, or is this just something you're worried about because someone said you shouldn't bend your wrist?