Then whats the use simple Rooting then ??
I'll tell you the benefits I got on my phone from simple rooting.
Completely remove ads from applications.
Voodoo sound really enhances sound quality(not available for your phone).
I can give apex launcher root access which is necessary to be able to set widgets from the app drawer like you can with the stock launcher. I am sure other launchers would have their extra functionality with root.
I can reboot my phone with a single click which is handy for phones with 512MB Ram but may not be big deal on galaxy nexus.
Able to use applications like poweramp, magicbutt live wallpaper and TSF shell launcher without having to pay. You cant use any of those apps for free without root access.
I can backup all my app data which was not possible without root.
My advise to you is to go one step at a time. Root your phone and enjoy the power of superuser access. Once you are bored again then perhaps time to delve into custom roms.
1.All ROMs based on the stock ones are normally stable, since the G.Nexus is already using stock ICS and the sourcecodes are fully released, AOKP/CM9 will have the least bugs.
2.Not all custom ROMs require a factory wipe when upgrading to a newer version, its mentioned whether a full wipe is needed or not.
3.Some people want a change in the UI after a while or a bit more customization options, you don't need to be an enthusiast to do this and neither is the stock ICS experience so awesome that people wont want more.
1. The roms which use custom kernels for better battery and more performance etc are 90% of the time not nearly as stable as stock kernel. You will get a random reboot once in a while. Not every custom kernel works the same on every phone and it can take time to land the perfect one for your phone. Serious tweaking to the phone only really happens with kernels.
2. Most do especially significant upgrades.
3. You can use launchers if you are bored.
All I am saying is that it is not a good idea to suggest custom roms to someone who clearly doesnt feel very comfortable with all the things. He has never even rooted a phone...