For many years now, Thailand has had a declining birth rate.
There is (legitimate) concern that, at some point in the near future, Thailand's working-age population will begin to decline.
Anyone on this Forum has seen the emerging effects of this at gas pumps, restaurants, domestic-help options, etc.
It is too late to try to reverse the modern Thai preference for small families and few children.
Thus, in order to meet the near-term labor-force demand and need for eldercare, it makes sense for the Thai government to ease the way for migrants from Myanmar, Laos, and Cambodia to help fill these gaps -- due to the migrants proximity, ethnic similarity to Thais, Buddhist religion, and shared indigenous customs (e.g., Songkram, etc.).
For those of these cross-border migrants who spend a significant time in Thailand and can assimilate to the local culture and customs, that investment in the Thai economy and culture might be a viable pathway to citizenship.
It is a trend that we will increasingly witness around the world as some countries have aging populations while their neighbors are still "young."