- Edited
I think my suggestion was very reasoned and a lot more reasonable than that "we can offer you a bigger downoad limit for more money" reply.
Increasing the download limits for long-term continuous subscribers would increase the motivation for them to actually stay subscribed in order to not lose the benefits. Customer loyaltly is crucial in the subscription business and more long-term subscribers result in a much more stable business for SLR. Granting more downloads to long-term subscribers shouldn't result in more server stress on the average because there's little reason to believe that these people who are already using the site for months or years suddenly now just instantly download everything only becaue they have a higher limit. It's just some additional convenience for the long-term subscribers with zero to very little direct costs for SLR but actually a better customer retention which might result in additional profit.
Offering an extended downloads option for normal subscriptions has pretty much no long-term effect and might actually piss your long-term customers off since they already paid SLR a lot of money for their ongoing subscription. And such an option would in no way prevent download scamming from new "customers" who subscribe to the site only to download as much as possible on the first day.
So it would be a win-win situation for both SLR and their most loyal fans/subscribers.