The way to improve a product isn't to scrap it and build a new one every 6 months,
Lets not exaggerate. Google Talk was introduced 12 years go. Hangouts came 8 years later. Allo, 3 years after that.
I understand that it can be tough to let go of old applications, but sometimes a software company can no longer support it.
For old desktop programs, that just meant that it may or may not work anymore as systems are upgraded (as long it it uses only local resources and just isn't a client for an internet service). For web based applications though, it means they go away. Either embrace web based software and accept that or stick to traditional style desktop software.