Do good Intel officers need to have combat experience?

I think it is a good idea for an intel officer to be branch detailed to a combat arms branch during their Lieutenant years. As a combat arms officer, you will have a lot more leadership opportunities than you would as an MI LT. Second, your time as a combat arms officer will serve you well after you graduate from the Captains Career Course and find yourself as the Battallion S2 of a manuever battalion. You will be able to speak, and think like a manuever officer which will be key as you play the role of the enemy commander during MDMP.

I would highly recommend a branch detail as there is very little leadership opportunity for a 2LT in MI, when compared to a stint in Armor or Infantry.
What does a 2/1LT in the MI corps do, well they sit around and make coffee, unless they are fortunate enough to get a rare platoon slot.
Go the detail route, you won't regret it later in your career.

At the JO ranks, unless you are a lucky ducky and get with scouts, you aren't going to do much besides push paper. Regardless of where you go, and what you do, master your job and become the SME.