@Ash: that would be a question best left up to GE to answer.  I just bought the pair off of a retired lineman who had some that had never been used.  I assume they put it there for a reason

An energy impulse such that will RD the MOV, a standard magnetic ballast won't even notice. So with MOV you have now a tripped circuit or non working luminaire (if there is a fuse inside it), while without MOV there would not be any failure at all

They make sense only for protecting Electronic gear, where they actually lower the chances of failure resulting from an impulse

While the Ballast might survive a some large surge hits, if you have a large enough surge you might have a insulation breakdown leading to failure of the ballast, lamp or both and while the ballast might still work it might have exposed areas that can lead to arcing followed up by a fire. Yes I know this worst case scenario but this is how engineers think and they have to work with the accountants so cost is also a contributing factor..  Normally MOV's are designed to be an expendable component protecting the rest of the equipment downstream, while it might seem like a pain they are really there for a reason, if you need a reliable light fixture consider adding additional surge protection like a gas discharge suppressor, or simply fuse the MOV with it's own fuse so when it goes up with a bang it will take out the fuse and the lamp should just keep on working with no protection, while not the best idea if lighting is more important then a ballast / lamp failure it's an option ...     

If you have a surge that causes breakdowns on wiring, MOV wont really save you. MOVs of te sizes used are capable to sink enough to save semiconductors, but not more than that

MOVs are a cause of fire when you have an open Neutral or when they degrade after previous surges

Gear enclosures are designed to contain nasty gear failures, the most common of which is capacitor failure (sometimes explosove). The optical enclosute of the luminaire is designed to contain lamp explosions. Absence of MOVs is not a fire risk on any scale. Bad design of luminaire is

Concerning its a US store and I'm from the UK this news felt like a kick in the balls for me too  as I'm up to the wall with the LEDisease where I am

Last time I checked the HomeDepot where I am still had a limited selection of HID , mostly 175w Mv, 35w HPS and 70w HPS but I never buy those in store unless they are on sale with a huge discount. My online supplier had a much wider choice for less anyways