I'd agree with that Trystan if they were offered the free weekend once and then after that it was only open and available to those who hadn't used it before. As it is, these free weekends are open to anyone and a lot of people, who have no intention of taking out a subscription, wait for them and use them.
That was the model FindMyPast used when they first started offering free access periods; I assume that they changed because they found it was counter productive.
Another restriction that is tried is to limit the free access offered, for example various record sets (original images rather than transcripts) are excluded from the free access content. To see the original image the individual has to pay a one off fee or subscribe.
Another poster suggested free access was part of their contract, not so, the internet providers pay hard cash to licence the various records. He/she may be confused by the digitising contracts that do have a condition that the GRO receives a copy which provides users free access at the archive.
FindmyPast recompenses subscribers by extending their subscription with additional days.
Subscribers also benefit in a way they possibly do not realise. The free access periods allow the techies to monitor how the site responds to additional loading. This allows equipment to be upgraded if necessary or additional servers added to allow better load sharing
I would ask the people who object to free access for others. Are your opportunities for research so limited that you cannot avoid using that particular provider on the few days a year they offer free access to others?
Perhaps you could visit graveyards or archives to check records that have not been digitised on those days.
Finally I would note that there is one other reason for providing free access.
All the large record providers are actively talking to archives who hold records, if they can provide figures that show the archives they have x number of visitors to their site they are more likely to convince the archive to sign a deal with them rather than another company.
The more deals that are signed the more records are available online.
You the subscriber benefits in the end.
Cheers
Guy