Hayden
Your argument is all about real F1, here we're talking about iGP. Personally I don't have an issue with a host selectable "No Refuelling" option, it allows for both sides of this debate to have what they want and that must be a good thing.
The drawback for me isn't the rule, it's the fact that it will provide another split and therefore potentially another doubling of league numbers when we have enough trouble populating the leagues we already have.
As for strategy... I'd certainly be prepared to try it for a season. Currently the overcut is king because a set of new tyres doesn't overcome the fact that you leave the pits heavy with fuel. The cars that stay out on worn tyres and low fuel are, in may cases, faster.
With a no-refuelling rule it would presumably favour the undercut and would also help you if your tyre life was better (because the undercut might leave you with very worn tyres at the end of the race. This makes T.E. design more influential. The fact that you're fuelling for the entire race also makes F.E. design more important. Imagine having to carry 10 litres more than your opponents because you hadn't bothered with F.E. but they had. For the first half of the race you would be at a major disadvantage.
Finally risk... Do you load just enough fuel to complete the race and risk a DNF if your car runs out in the last couple of laps of the race or do you play safe by loading a few litres more than you need and spend the entire race dragging unnecessary weight around?