Can you come up with any logical reason against it?
But sure, I can elaborate on the one I already gave. The problem is that loyal and active players with 10 high level characters want to participate and win prizes in the GM hosted events too. (Those require a level 1 character on the same account)
The reason, or rather the benefit, of the change is to increase inclusiveness and happiness.
I don't see any (real) increased cost. One argument I could see is that it attracted hackers/cheaters. To deter them, a GM just has to ask everyone participating, before the event starts, to whisper him the character name that would win the price. This is close to zero cost with a chat macro and an addon like WIM to track whispers. A quick Lua script to detect duplicate names catches those that try to buy a win or increase their chance by having friends helping out.
Yes, it is a personal issue which is also shared by other people.
This is a section of a forum to give suggestions to change/improve the experience. This suggestion qualifies as such.
Looking at your other forum posts, I can see that you are either confidently spouting wrong information while being toxic and passive aggressive, or a troll. That's why I won't entertain you any further.