This is timely as I just invested in a new suit for myself, but I don't disagree with Cuban's take on things. If you're a guy, you probably should have a nice black suit in your closet for certain occasions -- black works well for weddings, funerals, and if it's nice enough, formal dinners and parties. On the whole, however, I very much dislike having to wear suits at all and do not disagree one bit with what Cuban says in his post. My $0.12 on purchasing suits is that if you are going to make the investment, you should spend enough to get a suit that looks custom-tailored and that is extraordinarily light and comfortable to wear.
I remember when I was looking at jobs after graduating from college and some companies were offering "wardrobe bonuses" to allow new college graduates to go out and purchase a bunch of suits so that they had the right "uniform" for the job. I love Cuban's take on this:
Give your suit wearing employees a raise. Tell them every day is casual day.
My biggest personal argument against suits has always been that they do not help you do better work -- wear what you are comfortable in and produce extraordinary results. Change your dress code policy simply to: "You must."