I dunno. Maybe because we are playing a cooperative game? And I already spent mine on something that saved your bacon?
There is no "mine" in, "if the dragon's breath recharges before we kill it, we are all toast."
It's not like
not using inspiration (or using it, but ignoring the option for passing to someone else) makes the game non-cooperative...
The weirdness of this "player handing over inspiration to another" is that it has a faint shade of player-DM adversity. It sounds like it can be used when the DM doesn't grant player X inspiration, and player Y disagrees and steps in granting her own. So the DM has decided it is
not enough to grant inspiration, but the player can override the decision (although at a personal cost)... it doesn't vibe with me.
On one hand, it doesn't sound that different from handing over a healing potion, does it? On the other hand, it feels more similar to passing over your XP or a condition. To me it feels just as goofy as one player saying "hey your Wizard is near levelling up, my Fighter is far away, have 500XP of mine and the whole party will be stronger", or "I have this Bless bonus but I don't need it right now, let me pass it on to someone else". Yes, it's very cooperative, but it just doesn't feel right to me.
And possibly the second half of the reason is that it doesn't feel justified enough by narrative. A potion is an object, no reason to explain how you can pass it around. But inspiration? If you have become
inspired, how do you pass it around? I am sure someone immediately thinks "I make an awesome speech and inspire the others!" but the rule is disconnected from the PC's ability to make a speech, and it's way too open and generic... rephrasing the last question, if you have become
inspired by playing according to your values (e.g. being generous -> donating to the poor), how do you pass your inspiration
to a character that has different/conflicting values (e.g. greedy -> steals from everyone)? And even if you can pass it around by making a speech, why do you
lose it in the process?