Having Moore's law is it worth looking for more algorithms?
Yes. 


Better algorithms, that run in less time complexity - work way better than just an increase in constant factor for large enough input, but more transistors is just a constant factor of work.
We have reached the "end" of this "law". Now we are in an era where its hard to make transistors smaller due to quantum effects on them.
Having newer and better algorithms will make programs run faster on current computers, and we wont have to always buy new ones.
Why not have both? more transistors + newer algorithms = even better performance!