There can't be many EU/EEA nationals applying for naturalisation anyway, I would have thought. Unless you want to apply for a job in the army, become a politician with ministerial ambitions or contemplate being a high level civil servant, the only significant downside to not being naturalised is not being able to vote in general elections (except for Irish nationals residing in the UK who have that right anyway).

So, the main reason might be one of principle in acquiring British citizenship per se, out of a feeling of attachment to the country. However, the fact that you have to pay a substantial sum for naturalisation kind of destroys the nobility of the gesture and turns it, imo , into a commercial transaction. And, as a commercial transaction, it sure ain't value for money for an EU/EEA national.