I agree with others, it should be changeable: moreover, I'd appreciate if there was an option to move it from LMB/RMB to other buttons like 1 and 2 for example.
I use a laptop with these single-block touchpads and thus click and hold doesn't work for me that much because of how the computer receives the input.
Perhaps when I start using my controller again and/or a USB mouse I might be more open to the click/hold approach, but not so much right now.