As a frequent and long time visitor to Thailand, let me give my view. Many Western countries view Thailand’s stance on Russia and the huge influx of Russians especially to Phuket as a negative. In general Russian tourists are less polite and not popular with most other visitors. In addition, the prices in hotels are not competitive with other SE Asian countries. A high season beach front pool villa in Vietnam is less than half the price of a similar villa in the same hotel chain in Thailand.
Just saying.