The Thai economy is suffering related to a lack of foreign tourism, especially in local resort areas, where a lot of businesses have already failed.
There are different "Phuket models" being considered related to re-opening Thailand to tourism, all of which seem unworkable to me. Having visitors spend 14 days in quarantine won't work because that's their entire vacation time. Having tourists either semi-isolated or not isolated at all, versus doing a conventional quarantine, will resume the spread of the pandemic, even with testing, since the infections aren't detectable right away. If you don't isolate the Thai locals on the island not only will other guests be infected with corona virus, but the disease will return to the rest of Thailand too.
Some people say that the current economic impact is too great, so there is on other choice, but that fails to consider the economic impact of shutting the country down again for another two months. Domestic tourism would stop, and businesses like restaurants and movie theaters would close again, not to mention the impact to schools. Some small businesses must have failed during that first three month closure.
The only workable alternative is to open to longer stay visitors who do a quarantine. A vacationer here for 3 weeks still isn't going to have time for that stay to make sense, one extra week after the restriction, but someone spending 3 months to a year here would. I don't get it why this isn't obvious.
There are 28 million Americans between the ages of 65 to 84 who are at elevated risk of death from this pandemic; some of them would like a nice long break, and for many of them finances are relatively available. Asking them to pay more for quarantine, health insurance, and testing expenses would be no problem, but Thailand would also need to make that reasonable, to not require that everyone gets redundant insurance policies, for example. That US stat is only to indicate the potential visitor base in one country, of course; people could have their own reasons for visiting from different places.
I think the concern is over Thailand just spending a decade weeding out a lot of long-stay visitors who caused problems, under the table English teachers, fugitives from the law from elsewhere, grifters, etc. And the general impression of sexpats isn't always positive. Still, they need to push through such preconceptions to figure out plan details that will work. And sooner is going to work better than later; it would take time to add a few hundred thousand long-stay visitors, and that's the scale of additional residence that would be required to make a difference.