I disagree. The x-antibody part of the events is a bonus, the normal part is already good on its own (at least in the events we are having, omnimon SP is good and nefertimon is decent). The good thing about XAB not being available in large quantities is that it forces players to choose what they make, which is hopefully going to create variance in people's teams.
I wouldn't compare X-AB with Burst capacitors: the latter is pretty much necessary after a certain point in the game, the antibody isn't. I could see putting the first X-AB in the rank rewards instead of top1000,though.