It doesn't.
There are a couple of optical illusions that make it appear more expensive than it really is.
First, compared to the rest of the services we offer, the price of a support subscription is relatively high. If you want to make something look bigger, set it next to something small. (If we went in for manipulative marketing, we'd do the opposite: offer some hugely expensive incrementally better alternative that would make support subscriptions look like a bargain by comparison.)
Second, other providers tend to charge everybody for support whether they use it or not, either with a flat monthly fee or by hiding it in the cost of other services. This makes the cost of support appear lower than it is because if one person in five uses support, that person only has to pay 1/5th of the cost. But the other four are subsidizing him, getting nothing in return and there's nothing they can do about it. We refuse to do that. Our members will always have a choice.
Like the rest of our services, the price of a subscription membership is based on the cost of providing it; providing high-quality support is really expensive. And in addition to the cost of actually providing support, there are significant ongoing costs associated with making sure someone who knows what they're doing will be available when support is needed.
We've experimented with several models that offer less support at lower costs, with invariably poor results. Underfunded support leads to a soul-crushing contest to see who is more miserable: the members receiving inferior support, or the people who have to provide it. That's a game with no winners, and we won't play it. We are interested in providing support in one of two ways: really well, or not at all.
So, support costs (you) what it costs (us). We feel the subscription membership is a very good value that gives us what we need to be able to take good care of the people who select it. But what makes us really different is that we make it opt-in in an industry that usually doesn't even let you opt out.