Thank you
for all the replies.
Strictlybojack has summed up what I was getting at, in his reply #170. This being that the money saved by not fitting the handgrips (and I appreciate of course how it all adds up) is not proportionate to the additional money which can be charged for one that does have a grip. As he says, it's about creating a tiered market and showing how much more one gets for the extra money one spends. Though savings would clearly be made by not fitting the handgrips, it would have still been quite likely that those cleaners which did have them brought Hoover more revenue overall as they were able to sell them for a disproportionally higher price.
I once knew a Hotpoint rep who told me that they encouraged all store staff to sell from the mid & top ranges, for example the Aquarius and Ultima laundry appliances, rather than the First Edition, simply because the First Edition machines cost roughly the same price to manufacture as all the others, yet the prestige nature of the alternative ranges and the minor additional features added pounds to the selling price. The problem Hotpoint (and indeed others) had in this instance was that the profit the stores made on the goods was pretty much always proportionate to the cost price they paid to the manufacturer, so for the store there was not a great incentive to worry too much about up-selling. However, for the manufacturer, the money they made on the higher specification machine was, as I explained, completely disproportionate, so for them, more was definitely more.