The rule of thumb is to buy as much insurance as you can afford. It can be hard to decide about such "extras" as uninsured and underinsured motorist, especially if your insurance agent and financial advisor are giving you conflicting responses. From what you have explained, I would keep the coverage. Its premium is usually a small portion of your total premium.
Like all insurance, you wish you had more ONLY when you need it.
I would suggest contacting the Arizona Department of Insurance consumer division for auto insurance. Having the AZ state facts about how often this type of insurance is needed, etc. at their fingertips, they should help you make your final decision regarding this type of coverage.
Get a car insurance quote for uninsured motorist with us and it may be cheaper than what your agent is offering.