It is normal, that countries, who represent 80 million people, have a bigger say in things, than contries that represent 10 millions or less. In a democracy the majority rules, nothing new about that. Every member country knew about that, when they joined. They were aware, that their influence is proportional to their size. Everyone who cannot cope with that, is free to not join (or to leave again).
No one is being forced to become a member of the European Union but if you join, giving up some sovereign rights is part of the deal. No secret, too.
When it comes to ruling such a huge and complex entity, it cannot be allowed, that the tail waggles with the dog, if you know what I mean.