Higher end lights also have reflectors built to put the majority of the light in your tank and on your plants or other inhabitants, which is why shop lights aren't that great if you have creatures that need a certain amount of light. Fish don't need a certain amount of light so it's not necessary.
I used to grow plants with shop lights on my 125g but it takes a lot more shop lights than just getting a single CF light with the correct wattage.
I don't see the problem with hanging shop lights above your tank if it's simply for viewing. I'm planning on doing this with some of my tanks when we buy a house. It will make maintanance easier too since I won't have to worry about getting the strips wet or them falling in, or having to take them off when I'm doing maintanance.