History shows that MS supports their new consoles very much in the first few years but plateaus off in the latter part of the life cycle while Sony brings a consistent supply of exclusives year after year up till the end of the console's life. Not saying this is the case for this gen but could explain what we are seeing now. Of course, with Phil at the helm of Xbox, that could and hopefully would change.
You are forgetting sony absolutely sucks at the beginning of a generation and this has been the worst sony console ever for exclusives thus far. Even with plenty of time to prepare and ease of hardware development compared to ps3. No doubt they will have the games eventually, but it just sucks because this generation has particular weak consoles, so the differences compared to current tech will be apparent even faster. So we have to wait as the console slips further and futher behind.