To clarify this, there are two levels.
Being required to file even if you'll owe no tax, and being required to file if you do owe.
Not everyone is required to file at all.
As far as how aggressively they're going to enforce this stuff on foreigners who aren't working or earning money otherwise in Thailand, nobody can say.
So I guess it's best to assess your personal situation, which really will be different for each person, and make your own decision about compliance.