That's what I'm thinking too. I tested it in a few games without any modifications to the hero, then I opened all the free packs and runes that came on the test server and tried to boost my hero as much as possible and see the difference. While there are some advantages (and more as the hero boosts grow), I think one can easily play with the hero without any boosts, if the gameplay remains like this.
Especially if you have a strong deck in Splinterlands, you can manage with a weak hero. That's my first impression.