Well, I guess I'm the odd man out. No, you don't have to worry about the inside of your brass (unless you have spiders living in them). And no, you don't have to have shiny/glossy/high polished brass. I reloaded for mebbe 12 years before I got a tumbler. I wiped each case, as I inspected it, with a rag lightly soaked with mineral spirits. The important thing is that there is no grit/sand/dirt on the brass that will imbed/scratch your sizing die. Unpolished brass will not wear out your dies faster, and if you just use your eyes, finding defects is no harder than with polished brass. Before my tumbler came, I was reloading .223 and 7.62x39 a lot, besides my handgun ammo. If I wanted "BBQ" ammo I would polish each case on a mandrel with 000 steel wool.
Some fellers talk about "Pride in Workmanship" and that's fine, but on a small budget and I was the only person to see my reloads, dull, unpolished brass worked fine...