We woke up one morning about three years ago and said "Okay, things can be better. MAME is already great, but we can do better and be friendlier."
It takes time to get the gears moving, and there's a lot going on behind this that I'm absolutely excited about but can't talk about because we're looking at probably six months to a year of work to get to.
What I can say is that if everything goes to plan, these changes are going to make the 0.106 overhaul (which was the largest redesign of MAME to date!) look microscopic by comparison.