While it is definitely true that in such case English would be quite fair inside of EU, it also puts EU in worse position in outside world where USA have those advantages...
Beside that there is a viable alternative. Remember that Izrael has revived its ancient language, and Indonesia created a new one based on language of one of their small islands. That language united nation of hundreds of millions!
We can use Esperanto. It is artificial in origin, so no one nation speaks it natively (native individuals do, but not nations). It is designed to be easy to learn and use (I personally confirm it - 2 years of autodidacticly learning Esperanto was equivalent of 15 years of school learning of English). So even people who never heard about it can very quickly get to very usable level.
And possibly the best part is that it can serve as a language that units humankind as a whole. We all can preserve our national language for national communication and use Esperanto for international communication. This will not happen tomorrow, but with political support it can happen quickly. Until then, many people, as me, use it daily and support it's spread.
The fact that power of speakers matter is very valid while those speakers are centered on the ethnocentric level of care, or lower (see eg Integral theory by Ken Wilber: Loevinger; Spiral Dynamics etc). But when society as a whole develops, they care more about other groups and humankind as a whole. Then it is much easier to do adopt a lingua franca than serves them all rather than just forcing smaller nations to use language of the hegemon of the time.