with Taproot~more complex scripts are now possible and I expect to see this in near future.
We are already seeing them on blockchain for example
this is one of the earlier Taproot transactions that is using the new OP code and the script spending path.
With all bugs and hacks we see in smart contracts I don't think it's smart to implement this for Bitcoin right now.
Those bugs aren't because of the smart contracts or their additional capabilities, they are mainly due to developer incompetence and lack of code review that sneaked some vulnerabilities into those altcoin protocols.
The reason why we aren't adding that kind of functionality to bitcoin is mainly because it is not needed in a payment system and so far there hasn't been any serious use case for them either.