Final Fantasy plays a bit slow. One of the biggest complaints of the first game would be how that wen you select a target and that target disappears during the turn, the action becomes invalid. This was changed in the Playstation remakes onwards to match the later games (FF4 onwards I think?) but there is one big key here: In the PS1 version only, there is an option to disable this retargeting.
While it speeds up the game immensely to have the retargeting on, a huge part of the strategy of the game comes from proper targeting. Now, here is the issue. In FF1 all of the bosses are single targets. In random battles, you want the game to go quickly. But in an important battle, targets disappearing or the like to make moves pottentially not work would of course be furiating but would make for planning and pattern watching that is otherwise not available in a turn based game.
This value of time, however, is not found only in the battle system of Final Fantasy. The dungeons are littered with treasure chests, some often within view but requiring you to maneuver around the playing field. Playing the game as a youth, I would often stumble across a chest with a piddly amount of Gil or a mere Potion. "Stupid designers," I thought. "Who wants these worthless things? They do not know anything!"
How little I knew. With resource management being so important in FF1, deciding whether the potential rewards of that chest are worth the risk of getting into a battle that might lead to the running out of resources right before the boss fight, each chest seen poses a question. Is it worth getting it right now? That chest might make or break the entire run. I could lose so much time.
I found the Playstation port of the game to be significantly easier, nullifying many of these questions and thought. This did not make the game less fun, but took out a very important aspect that, while perhaps not perfectly implemented, deserves further exploration in more games.