Okvid, let's say that you're stranded on a small, deserted, tropical island with only coconut trees. would the supply of trees be optimal? the answer depends on your preferences. let's pretend that mango is your favorite fruit. if a mango tree was somehow magically added to the island, then the supply of trees would be closer to optimal. you would derive more benefit from the supply of trees.
one day i somehow end up on the island with you. in this case, the optimality of the tree supply depends on our preferences. i love durian, you can't stand it. however we both love jackfruit. therefore the addition of a jackfruit tree would provide greater total benefit than the addition of a durian tree.
in all cases the optimal supply of fruit trees, and everything else, is a function of everyone's preferences, which are most accurately revealed through personal sacrifice. if donors to the huntington are willing to make a big sacrifice for tropical fruit trees, but the huntington only plants a few tropical fruit trees, then the supply would be very suboptimal. it wouldn't provide nearly as much benefit as it could and should.
your argument against using donations to reveal our preferences is that the durian category would receive too much money. but that's like me arguing that huntington donors would allocate too much money to renaissance paintings.
do i like renaissance paintings? well, not nearly as much as i like tropical fruit trees. but this doesn't mean that i would ever oppose people's freedom to use their donations to express their preferences.
right now people have the freedom to use their donations to express their preference for this website. we all benefit from this freedom. but there isn't a single donor who appreciates all fruit discussion equally. so we would benefit even more if donors were free to use their donations to express their preferences more specifically.