I suggest allowing that every block turns into something, like when breaking packed ice or glass, otherwise there isn't enough fun in breaking blocks. I've heard my friends complain about it and I suggest when blocks you can't typically break without silk touch should be breakable.
This is actually an intended feature. The item that is being randomized is the drop, not the block. If a block does not drop anything (for example, because you are not using the right tool, or the block does not drop any item like Dead Bush), no items will be randomized. At the same time, anything that drops multiple items (for example, cows, spiders, lapis lazuli block, redstone, etc..) will also drop multiple items. This gives players access to an unique feature: putting items that cannot be placed (and any item) into containers like chests, furnaces, droppers, etc and then breaking the container will randomize those items further, as breaking a chest full of items will drop the item inside the chest... and those items will get randomized as well.
I am sorry you don't find PlayUHC's randomizer fun, but that is how I intended the game mode to work, and it is "unique" compared to other servers. Some people would like me to conform to what other networks do, but that would make no difference between this network and other networks. Having blocks that do not drop anything without a specific tool may make the game mode harder compared to other networks, but this is an ultra hard core network: if you want to be good at this game mode, you'll need to develop the required skills.