I was not so happy about this either. But This is how I use it:
I have a rule for example 10 % discount. Making the following categories:
and so on
You do have to do a discount rule for every combination, but not for every Product. I use around ten discount rules which covers my needs. It could also be based on value instead of percent, -100, -75, -10 and so on.
I just add the Product to the appropriate category an voila, correct discount. As a bonus I can see which Products are on 10 % discount by checking the category.
Combining 30 % and 10 % is a bit trickier, because you get 30 % discount on the original price and then 10 % of the already discounted price. A total of 37 % discount.
It is not a perfect system. But it works. Loading new prices with csv might be more efficient. Before I had to manually search for every discounted product, now I an see which category it is assigned to or search by category for discounted products.
Jörgen @ Kreativ Fotografi