Is this good with the rules-as-written? Obviously if it works for me, no problem, but I'm trying to stick to the rules for awhile before branching off and tweaking things out of alignment. ;)
From book-examples, there's nothing saying that a character without a Detect Secret Doors ability couldn't look for secret doors anyway; they just don't get any extra dice beyond - in this example - Discernment.
So that's how the sibling and I have been playing the last couple of games. I imagine that in a game with a full-fledged (mis)adventuring party, it's less of an issue, but with a single character, it helps to give us more options.
Initially, I'd decided to increase the difficulty for a task that was suitably Ability-like if you didn't have the Ability itself; Climbing is pretty generic, for example, but Detect Secret Doors is a little more specialised. In the end, though, this had a couple of problems: it relied too much on my whim deciding whether or not a given task was "ability-like"; and most characters are going to only have 3-4 dice in a given Attribute anyway (for the first several levels, at least), so unless the task was Easy or Medium anyway, the chance was pretty low.
Anyway. I think this is pretty spot-on, but after a couple of years of D&D and coming to rely on this kind of thing being spelled out, I'm slightly anxious when I come across one of these nebulous rules situations.
Anonymouse,
You can totally use Attributes with no Ability. In fact, it's one of the most fun parts of the game.