The crucial distinction is this: do you appreciate the rare object for its own attributes, or do you appreciate the rare object because you have it and other people do not?
If you loved the plants (or crystals, or antiques, or anything else) for their own sake, reducing scarcity would not harm your appreciation and enjoyment. If your goal is having what others cannot, the collection might as well just be numbers in a bank account: a proxy for power.
Can't you also value a thing for the history they represent? The tomb of the unknown soldier isn't sacred because it's human remains, they're sacred because of their story.
If what makes our houseplant special is a result, not of the evolution of the species, but of modern laboratory manipulations, do we perceive it in the same way? Should we?
If you loved the plants (or crystals, or antiques, or anything else) for their own sake, reducing scarcity would not harm your appreciation and enjoyment. If your goal is having what others cannot, the collection might as well just be numbers in a bank account: a proxy for power.