Barry Schwarz’s work on The Tyranny of Choice makes it clear that fewer choices lead to more purchases, faster and with less post-purchase regret. While common sense would say that more choice gives more utility, behavioural economics shows that complex choices usually result in no choice at all — and more importantly, no sale.
A range should only be expanded where it clearly makes the choice easier for a customer segment. In the right situation, adding a choice to the range can increase average weight of purchase, make the sales cycle shorter and even reduce post-purchase regret. But before you add anything new pull out the pruning shears and cut as much as you can.