Here is my example, first and foremost, so we are all on the same page...
The Standard Action:
There is the Standard Action,
Using a Standard Action to take the Attack Action,
Standard Action Attacks,
And "as a Standard Action..."
Now, what if we just had one, and it covered all those things? Why bother breaking it up, at all?
Vital Strike might suck less. Nothing game-breaking there.
Think about all the petty arguments around the petty differences that could be avoided by eliminating all the petty differences. Unless the petty differences exist specifically and solely to cause argument.
All the stupid time wasted debating pointless and irrelevant details... when we could have just been playing the game enjoying ourselves.
Has it ever really mattered if the feat said treat this as, and you were close but not exact? Maybe the content you are using came out after the feat. Does it even matter? Was it worth the argument?
Has gameplay ever been improved by crippling someone's fun just becauae you know the rules by heart?
The simpler method would have been calling "Standard Attack Action" instead "Single Attack Action", calling all special attack actions by the name of the feat/whatever that allows it (i.e. "Cleave Attack", "Vital Strike Attack", "Spring Attack", "Lunge Attack", etc.), and "Full Attack Action" instead "Iterative Attack Action".
But just as we "can't" just switch everything to the metric system because imperial is so standard, we "can't" rename things to something sensible to clear up the confusion, balance reasons aside.
There's probably something insane you can do with vital strike with all limits removed. Is it worth killing off all the reasonable things which aren't a simple attack with spring attack and vital strike? Especially since flyby attack does work with any standard action? Not IMO, but that is just my opinion.
I guess several GMs would allow the Spring Attack and Vital Strike combination once they checked the numbers or saw it in action.
But IMO Spring Attack is not about maximizing DPR. If you don't have to worry about AOO from a chosen foe, you are more free to position yourself as you like. And as soon as you move away after attacking, you deny your target their full-attack but still get their attention. Hitting someone only once is not that spectacular, but the fact that they can only hit you once in return buys the rest of the party some time to act. Dealing some more damage with your Spring Attack is somewhat helpful for your mission (keeping opponent engaged in low-stakes fight), but not essential.
Now this breaks apart next round, when the foe closes to you and you can't Spring Attack away. But if you want to continue the dance, you can by using Vital Strike and moving away afterwards. Depending on the foe, an Acrobatics check or relying on Mobility works better to avoid an AOO - in some cases you simply might want to stay, though.