I’ve always approached H&S products as being the natural ‘dinner’ option in the Huel lineup.
Being an adult male, a 400 kcal dinner isn’t really viable, so I always have two. The H&S products being sold with an odd number of servings is therefore super inconvenient; it means each purchase is (for me) essentially 3.5 meals. Far from life-ruining stuff, of course - and it would never impact whether I buy H&S, but it might sometimes affect how many I buy, just because it slightly dilutes the convenience-focused nature of Huel products. This leads to me having more of a drive to consider other options at least some of the time.
As someone who has just returned after a two-year hiatus, I want some Huel Black Edition for lunches, some Hot & Savoury for dinners, some Daily Greens to plug any gaps, and probably some Complete Nutrition Bars for both the sake of having a treat, and occasionally just for the sensation of having something to bite & chew.
(And did I mention I’d rather not be limited to having literally the same flavour every day?)
For me, the advantage of Huel is it manages to be a convenient healthy option which interferes with my habit of lazily just ordering an unhealthy takeout after a long day because I’m tired and I can’t be bothered. The main disadvantage of Huel is not that it is inexpensive in a vacuum, but that the combination of the product quantities & various incentives (e.g. free shipping) means you always end up with bulk purchases to some extent. So in that context, the Hot & Savoury selling with an odd number of servings is disproportionately painful - the subscriptions are already a bit ‘spikey’ financially, so the instinctual “just buy two of each” doesn’t feel great…
I am trying to be quite specific on my use case, as I have no idea what proportion of Huel customers get most or all of their calories from Huel products (and I obviously don’t expect changes to be made just for me). If I’m statistically a weird edge case that it isn’t justifiable to cater to, fair enough - just wanted to offer my $0.02. 
