I don't see why that's a problem? If you've created and released better software, why wouldn't you want your users to update?
Core devs have a little bit of a different idea then you of what Bitcoin is. The whole premise of it is that Bitcoin is a stable and secure network.
There are plenty of coins with a lot of new features on a network and client level and Bitcoin will never be able to compete with that.
Instead, as the oldest cryptocurrency Bitcoin has been developing as the most stable and secure, where even small changes, like scaling issue, is very rigorously discussed. You can see that it took a lot of drama to implement a simple change and Core devs didn't even want a hard fork if they could go around it. That is why segwit is a soft fork and as a soft work, old clients don't need to upgrade.
Core celebrates the fact that it is the oldest coin and it respects that through not adding much change over time and instead focusing on improving and rigorously testing the already established features. Core wants Bitcoin to be cryptocurrency first and all the other features are completely unnecessary to it.
There are many of cryptocurrencies out there now, but Bitcoin is most developed, most adopted, most secure and most stable. That is what Bitcoin is in the eyes of Core team and a big user base behind it.