If you wanted a dedicated Macro lens that you only use on a tripod, then I suppose not. But, I shoot a lot more at "near macro" than I do true macro and I like to wander around outside getting close to things.
Shooting macro in the field is very difficult. People who don't do it regularly don't always realize just how tricky it can be. It's a real challenge to get the tripod exactly where you want it to accurately frame the image in the the way you envision it.
Remember, everything is magnified. The light can be perfect in one spot for 30 seconds and then a tiny shift and it's gone. An insect on a leaf will move out of the frame. The slightest breeze and your perfectly framed shot suddenly has shifted. An image looks perfect when you are kneeling on the ground, but shift your back slightly, and you lose it.
I can't count the number of times when I've started out using a tripod and just gave up and switched over to hand holding, because I couldn't possibly position the tripod precisely where I wanted it or do it quickly enough so as not to lose the light or the framing.
Oftentimes I find myself framing an image, pre-setting the focus and then physically moving in closer or further away as I try to get the most interesting part of the subject in focus. That's pretty much impossible to do with a tripod, and the IS definitely helps.
Plus, it's a great portrait lens and modest telephoto. Both things that make the IS very valuable.