Why is that weird? Literally every time they talk about fusions, it's to point out that the power of the fused form is exponentially higher than that of the individuals themselves.
A running theme of Super (as least as far as I can tell) is that the forms Saiyans attain isn't all that important. Hell, when this whole thing first started and Goku was fighting Berus, he spent a good few minutes holding his own in his base/regular SSJ form after he'd dropped out of SSJG. Which is an accomplishment considering SSJ3 Goku couldn't even touch him.