Personally. I really think gloves are a good idea. Especially if cleaning, maintaining and working in tanks all day is how you earn your living.
First of all, When you have yours hands in water all day your skin becomes very dry and cracked. This leads to excessive use of lotion. This also insures that there is no soap residue getting in to my tanks, or other contaminants.
Second it protects me from nicks and scratches, allergie issues with some foods and it keeps my hands from becoming dried and cracked. Some times they save me from a bite.
Thats just my two cents.