I do not mind some random (input/output/whatever) as long as it either does not promote excessive grinding (tens or hundreds of boss runs for item and/or level grinding) or enable undesirable stuff easily and quickly bypassed or undone in favor of optimal results with a few quick reloads (e.g., open chest, trap stings you for damage, reload game, open chest, get powerful rare item, save game, kill the enemy). However, no random, and you can memorize everything in the game then try to devise the plan to win. For example, as good as Star Control 2 is/was, I still know exactly what to do and where to go to win the game as efficiently as possible after all of these years. (I may not remember every single detail, but that will not interfere with winning the game.) Or, I can look at Doom or Quake (or Super Mario Bros.), and crush levels (or be crushed if I try Nightmare and/or various unofficial conduits like pacifists not killing monsters). I cannot do something like this in Spelunky or various classic roguelikes. They are random enough that I cannot devise a single plan to win every game before I play the game then follow the plan mindlessly.
I dislike grinding for items or high levels in games like Diablo 2. It was somewhat amusing that guides lists the items you should use, yet many of those items were rare enough (especially really rare stuff like Jah and Ber runes required for Enigma runeword) that you would likely not find unless you traded with people who likely duped items.