Dragonball's biggest problem was that it started as a gag martial arts manga. Because of this, the characters often did ridiculous things early on simply because they were funny. Most notably, Roshi blows up the moon for a joke before Goku even faces his first (somewhat) serious set of villains in the form of the Red Ribbon Army. At the time it worked because it was really just a gag and no one really cared about how ridiculously powerful someone who could perform such a feat would have to be. But this caused a huge problem as the show became more serious and more obsessed with relative power levels (even putting an exact numeric measure on them) since there was pretty much no place to go visually to show that someone was stronger than Roshi.
Even if a villain blows up a mountain, it's not really much compared to blowing up the moon. The villain can't blow up the moon, since it's already blown up, and if he blows up Earth there's nowhere for the story to take place anymore. The series could still up the emotional punch by having beloved characters get injured or die, and it did have some success in doing this, but after you do it enough the audience isn't affected as strongly anymore, and the combination of the senzu beans and dragonballs meant that neither injury nor death was a permanent problem anyway. Thus all the series really can do is arbitrarily decide that character A is more powerful than character B, and as such when character A attacks character B character B takes damage but character A is fine. However, the series no longer has a credible way to demonstrate this power visually or emotionally.
The series should have either stuck to its gag roots, in which case none of this would have mattered much, or if it wanted to become more serious it should have scaled back the size of the conflict or alternatively put characters against so ridiculous of opponents that the only way that they had a chance of victory was through victory. Ranma 1/2 had success with the former route. Jojo's bizarre adventure famously had a lot of success with the latter route (just imagine if Part 3 had revolved around a race of super-super-vampires who were even more powerful than the pillar men). I think that Toriyama tried to do some of this by being just a little more creative with side characters, but ultimately it was too little too late. Even if Vegeta or Piccolo or Krillin or even Tien (who probably has the most interesting movelist, not that the series remembers anything about that) became the main character, we'd quickly get tired of their moves as well because the series would still ultimately be about continually fighting opponents who are arbitrarily more powerful than the last, but which aren't in any way more impressive than the last, which are then overcome by having our heroes become arbitrarily more powerful than the villains at the last minute.