I do for several reasons.
1) it would be more revenue for the company
2) it would ease much of the angst from FAs and inconsistencies in the EXP/Airpass/Concierge Keys free item in coach program
3) this is a group of workers that can't accept being the most overpaid and relatively least productive and underworked.

Why should they get a commission for the sale? It's not like they had to compel the customers to purchase the item, explain its features and operation-they simply collect the payment and fulfill the item. If I purchase an Audi A4, I fully expect the sales professional who takes his/her time working with me and helping me feel comfortable with my purchase to be rewarded. Not the case with the flight attendants.

I was on a CO flight last year with DirecTV and the FAs made multiple announcements encouraging passengers to purchase the service for $6-it's rather annoying and unprofessional.

Let's also remember that if APFA were to be compensated for those sales they'd still find something to complain about. For example, remember the $150 bonus checks they got and all the frustration with having to simply pick-up a paper check and be thanked for their service? I recall APFA sentiment that vendors adding commissions to their pay was simply a way for AMR to reduce its payroll expenditure. They could be collecting nominal $500-600/annual compensation from Skymall and they saw it as AA's approach to justify stagnant or smaller wage increases due to the supplemental income.

Bottom line is the company has asked them to do a simple, reasonable task to serve the passengers and offer an added convenience for those using Heathrow Express and APFA has refused to cooperate unjustly. It's unfortunate for people like myself and the OP who use the Heathrow Express when traveling to London.