It is not right to choose a piece based on its technical difficulty. However,as other people said, you cannot ignore it completely because you need to be constantly challenged for the opportunity of self-improvement. In general, technically challenging pieces happen to be very beautiful (not always true, though). Thus, it's kinda reasonable for people to go for more difficult pieces because they prove to be more rewarding in the end. But, if you play a piece just for the sake of difficulty, then you won't learn a lot from that experience. I, being a mere amateur pianist, usually go for whatever suits my taste. Somtimes some pieces that I decide to play are technically undemanding, while other pieces could be quite difficult. Being challenged is another important aspect of playing piano.