While I don't disagree that IP is important, I think UNO is a bad example. It's a card game, with a rule set. Consumers wouldn't be happy if Mattel changed or "brought innovation" to UNO. They expect UNO to be the same game they've always known. The same could be said for any board game / card game.
How many other IP can maintain decades of relevance in the toy industry? Mattel is lucky to own several properties that have stood the test of time, but they've only managed to do so through innovative product lines that bring new toys to market twice a year.
You can't "focus on top line IPs" without being creative and finding new ways to drive consumer interest in those brands.
I agree that recently Mattel has struggled with a certain type of "innovation" recently. Things like Sproutling, Nabi Tablets, Barbie Hologram, Aristotle, ThingMaker 3D printer etc. (the list of failed, high profile "tech" products from the past decade is a mile long) and launching new IP like Max Steel and Ever After High were dead on arrival, but that doesn't mean Mattel doesn't need to be innovative.
Fisher-Price is a good example of an office that knows how to do genuine, practical product innovation. Because their brand doesn't revolve around a single, generally static SKU (like a diecast car or a doll) they are constantly forced to come up with brand new products year after year, season after season. This emphasis on new ideas to drive sales, rather then relying on IP, demonstrates how effective true product innovation can be if done right.