You can ask the same for mycelium or bluewallet, why haven't they released a better app for desktop? Why are they just better in mobile mode despite being so popular?
Blue Wallet actually has a desktop app, but they don't highlight it enough on their website. They have big download buttons for their iOS and Android versions and a bit of text mentioning their desktop wallet. There is also a link to the
desktop version at the bottom of the site. Their OS choice is also peculiar. No Linux, no Windows, and only macOS.