Yeah a possible extra charge of £15/20 for download that's not needed, + an increase of 15mb more upload that users on the top tier at the moment have been waiting to be upgraded for a lifetime. It would be better just to upgrade the top tier package of 350mb to 400/35 than start a new top tier, from a customer point of view instead of making people who have wanted more upload speed for ages pay the penalty of paying extra for a download speed that's not needed.
But the business is run for the business, not the customer.
A downlink at 500 sounds a great product but that bandwidth will rarely ever be utilised apart from occasional speedtests to show it off. So it costs Virgin almost nothing to provide - it's all profit for them.
An uplink at 35 would certainly be utilised, so Virgin have to make it earn its way.