Because until border bounces are possible, they will lose too many foreigners if they remove the Covid extension. You may think that there are a lot of tourists in Thailand right now, but no, very little still. They can't afford to annoy the ones who still rely on Covid extension. When border bounces are back and buses go to borders every day, they will remove Covid extension. For now, people are flying to Phnom Penh to get tourist visa, it's simply not efficient enough so such Covid extensions will remain until border bounce reopens.
Just avoid Suvarnabhumi Airport, enter from Phuket, Chiang Mai, etc. Or if you enter via Suvarnabhumi make sure that you have an agent phone number to call to bribe your way in if they want to denied u.
Since you are an Indian passport holder, you should avoid entering from Suvarnabhumi, or make sure that you can call an agent to bribe your way in if you are denied entry. Some Indians and Pakistanis get quizzed heavily in Suvarhabhumi upon entry, they get ask documents after documents, and again, its at the discretion of IO which in BKK airport will give you hell a lot of the time. They are "afraid" that you might become illegal immigrant... or wtv, you know, its some kind of discrimination.