Honestly, timed events don't add difficulty. I know people who have anxiety problems and can't really function with a timed event because they cause panic attacks. The hardest part to any higher level activity will always be finding other people capable of doing the event, who want to do the event. Just look at the first raid. Leviathan is an easy raid; the communication required for leviathan is very difficult with random people. When the raid is considered hard because the gameplay is simple, but the required communication is difficult, it's poorly designed. Leviathan is artificially difficult. Don't get me wrong, I prefer rushing through content like strikes as fast as I can; but I don't expect anyone else to want to rush through content. But timers make players feel like they need to rush.