Tip for MSQ: watch the cutscenes. Actually let the voice actors finish their lines and enjoy seeing your character in the setting. Read the whole dialog. It will help you immerse yourself in the story. The story will be more interesting once you're doing the parts you haven't already seen.

As for long term play, it depends on what you want to do. The game is able to entertain someone for long periods of time assuming the player is willing to put in the time. Actually mentoring newbies, helping them, doing content with them and building a community? Time investment. Contributing to the hunting scene on a daily basis? Time investment. Raiding with a static whilst doing unreal, extreme farming, deep dungeons, ranked pvp and criterion? Time investment. Running your own fc and venues and arranging contests or events several times a week? Time investment. Committing to collecting every TT card, music, emote, fashion accessory, mount and minion the game has to offer? Time investment.

The people telling you to take breaks aren't doing the above. It's up to you if you want to.