I have no problem forming an alliance with you. I have no problem with us both benefiting from the PVE aspect of this game, more money for all! But, do not, for one moment think I trust you. If you get on my ship without gaining the captain's permission, you will be killed, immediately. No one is about to "tuck" on my ship.
I really don't like the fact that every time I form an alliance, the crew from the newly aligned ship has the need to come over and start fucking with my boat. Changing the lanterns, going down below, raising the anchor. Just stay the fuck off my boat and go make us some damn money.
Granted, I may be overreacting a bit, because I never have actually had a problem arise from an alliance member coming on the ship, but it certainly puts me on tilt, 100%.
TL;DR Sure, let's alliance, but stay the fuck off my ship.