I think Riot rushed the client and that's why it's such a mess

Either that or they just built the new one on the old, outdated bones of the old one. Look at the LoR client. They have the technology and aptitude to put together a clean, functioning client in this day and age, but they either didn't build it from the ground up (like they needed to) or they didn't take the time to make it work (which they also needed to). Truth is, it could have been delayed a few months to receive that much needed polish but it wasn't.