Ideally when renewing online you'd be presented with options. Say you have a $60 membership that comes with a $50 merch voucher. Why not give the option of spending it on a $50 'members pack' with the usual dross, OR $50 on a high quality shirt OR try to upsell them heaps of various packs. Do it all as part of the one process and you won't even hear a peep. Give the option to save it for later or use it on a gift card or donate it to charity or whatever else.
They're definitely going for a lazy tax approach and it'll work and save the club money but at the expense of devaluing our memberships.
Noticeable uptick in difficulty for the club to manage that system though (and thus more expensive). Now every membership they have to worry about who has selected which options.
If it is choice between 'usual dross' or voucher it isn't too much more complicated - do they send you A or B - but the more options the more workload each membership suddenly becomes because instead of a pile of A and a pile of B to stuff in the mail there is also a pile of C and a pile of D and arranging for someone else in the club to make a payment to a Charity and going into the team store to put together 'upsell pack #6' etc etc
Not to say there couldn't be some options but you don't want more than probably 3 at most I would have thought.
Plus the lazy tax is a winning strategy. By just doing the voucher they are using the simplest method for them to manage, with the likely highest financial upside.