I like the ability to change the skills and runes without having to go to town, it allows players to try all the skills and runes and see what they like more, but some people is complaining that we will have no commitment to our build anymore. I think +skill afixes on gear can help with that, but here's an idea I had that could maybe help having some more commitment and allow you to test all the skills at the same time.
They would only need to add some feature in town (nephalem altars again?), that will only unlock at high levels (45+ or so). On it, paying a certain amount of gold, you would lock your build, so you would not be able to change skills, runes or passives, but it would give a bonus to your character (+5% more damage, or +5% more damage reduction, or whatever they can think of. They can even let you chose the bonus you want from a list). This way, after trying all the skills, once you decide you like a build for your character, you would lock it and get a benefit from it. You could always go back to this altar and remove this lock, so you can change the skills again, but you will need to pay again to lock it once more and get the benefit with the new build.
Also, as some people will like to change their build often (pve vs pvp build, for instance), they could add an option to unlock a second build tab (costing a good amount of money to do it), so you can have two locked builds on your character, that can be changed without paying anything at the altars.
What do you think? This would add a bit more customization, have a bit more build commitment but keeping the hability to test everything.