Trying to have discussions with someone who thinks that they know far more than the other person and is incapable of accepting any counterargument is generally pointless, but for those reading this, I'm continuing.
Where did commoners enter into this?
Henry marrying the women he did is still a royal marriage, and I'm pretty sure all of his wives were of noble blood.
Edward IV didn't need one.
Did Henry IV need one? I don't think so, could be wrong.
Did Henry V need one? Not that I'm aware of.
Did Henry VI need one? No.
Did James I, II, and IV need one? I'm not sure.
This would put "yes" at a majority but not "only isolated incidents of no" - and of course, we're just looking at Britain for convenience.
The problem isn't "the Pope refuses outright". The problem is that you have to lean on him to get him to grant one, except for the most favorable pope-king situations.
And that doesn't mean the Pope will automatically grant one without any further adieu. I'm not saying its impossible, never have said it is impossible - just that the process is an actual process.
In Europe
These are just a few more examples, you know just for emphasis.
Ferdinand and Isabella had to have a papal dispensation, at least three of their four daughters Isabella, Maria and Catherine also needed them.
Philip II of Spain married as his fourth wife Archduchess Anna of Austria, his niece. Their grandson Philip IV married as his second wife Archduchess Mariana of Austria, his niece. Archduke Ferdinand of Austria married his niece, Anne Gonzaga. Archduke Charles of Austria married his niece, Maria Anna of Bavaria. The Emperor Leopold I's first marriage was to Infanta Margarita of Spain, his niece.
In the 18th century Maria I of Portugal married her uncle Pedro III (and, just for variety, an aunt-nephew marriage followed; their son José, Prince of Beira, married his aunt, his mother's sister). Francesco IV of Modena married his niece Princess Maria Beatrice of Savoy.
Papal dispensations were requested and were granted.