Is 'snecko eye' a bad choice without 2-cost cards?

A lot of players seem to believe that in order to make Snecko eye a good choice of boss relic, the deck should contain high-cost cards. They are hesitant to pick this relic up. The thought is that snecko eye changes the costs of cards to 1.5, and that therefore, compared to an energy relic, the snecko eye makes a tradeoff:

1. You get more cards to choose from;
2. Cards cost 1.5, so you can play less cards than without it when your cards are mostly cheap. So 2 cards per turn seems to be what you can do on average.

In addition, everything can cost 2 or 3 sometimes, allowing you to play only one card. Therefore, Snecko should rarely be picked, especially without 2-cost cards.

Is this assumption correct?