Personally, I'm happy with the price I've paid and redeemed the 10% and went to the free FFA Cup match. That being said, I know there'd be a lot of people who wouldn't have though and so I'm not surprised if they'd have a sour taste in their mouth, particularly if you're a family of say 4 - a minor discount would be fine but this is really quite large which I feel tarnishes the value perception for people having purchased full price memberships.
If the objective is to purely foot traffic then why not lower the base of the full cost and discount marginally for these membership drive days - I'd be interested to see the data post-season on avg. games attended from people who have purchased on a whim due to heavy discounts. As they've paid less, there may feel less obligated to attend due to their lower investment, they don't need to attend as many games to feel they've received value (e.g. deciding to go when weather is inclement or if you have an event clash).
Bringing down the base cost of the membership would reduce the barrier of entry for people signing up and make us less reliant on people signing up on a whim when it's heavily discounted - this way you still capture the rusted on but potentially raise the avg. games attended which translates into greater crowds and more $$$ spent in and around the stadium.
I find the whole discussion around memberships and pricing quite interesting, the other issue this raises will be people buying an active membership and then just sit in GA because that's cheaper than a GA membership and could leave our active area more bare than ever.