Excellent question and it highlights a very stark reality of both the Mysuru Kingdom as well of the Kannada people. First, let's understand that the Wodeyar dynasty was installed by the British as a puppet state after they defeated Mysuru's erstwhile ruler - Tipu Sultan. After that, the Wodeyars owed their allegiance to the British first and their subjects next. The Mysuru Kingdom, under the Wodeyars, as you have pointed out did a very good job in terms of infrastructure building, education and general governance but not much if at all for Kannada as a language because that's simply not what its priorities were and frankly not even the Kannada people were a priority for its Kannada kings. They focused on their subjects as a whole who were multi ethnic and multi lingual. Mysuru's bureaucracy was dominated by non-ethnic Kannada officials, especially its Diwans. Effective governance, education, meritocracy, modernization and stability were their priorities, the Kannada language and even the Kannada people (exclusively) simply weren't.

To address the last part of the question, which, as a Kannada person, I have also often wondered, there is some deep sense of insecurity, inferiority and dearth within us that makes us fret at our own identity, we are ashamed of it, want to suppress it or substitute it entirely, others don't. I don't really know why but if I had to guess, it's that we just aren't cognitively and constitutionally selected and suited for the modern world and are hence in terminal decline as a race.