Simply - most domestic electrical installations are billed based on a standard PF correction of around 0.9 to allow for losses in inductive loads in the users premises. The installed meter only measures 'real' power consumption and cannot correct for phase-loss.
If your home uses a LOT of inductive loads (motors etc) your supplier may well bill you differently to compensate for their loss i.e. calculate your consumption using a different (lower) PF value. This is common for industrial premises.
On the flip side, if your home uses NO inductive loads at all then you're being 'ripped' off to the tune of 10% as your bills are being 'adjusted' for no good reason! Most homes do, however, have inductive loads - transformers, washing machine motors, blower (heating) motors etc. Some of the worst performing items you can fit are CFL lighting where the PF can be as bad as 0.5 or worse!
It only becomes an issue if you have to power LOTS of them so the figure for VA is supplied to allow users that have 'lots' in use to compensate for the current draw by installing larger wiring i.e.
if you have 1 unit rated at 1000W (or 1100VA) it's not a problem. The difference between the current at 1000W and 1100VA is minimal and 'accepted' as a reasonable loss to the power companies. The difference in current is also negligible to your wiring.
if you have 100 units rated at 1000W (or 1100VA) then the losses to the power companies revenue (since they can't charge you for the 100 x 100 = 10,000W 'additional consumed watts') become appreciable but, NOT ONLY THAT, your wiring is carrying 10,000W 'extra' that, if you only took the 1000W basic rating at face-value (and not the 1100VA 'real' rating) to calculate your installation wiring requirement, would burn out your cabling!