Not good as in 'good VS evil' I mean good as in well written, or clever, or purely satirical (at least one of my characters is a parody of the typical harem girl) etc? I am aware that for "best" results I shouldn't use the 'H' word, since the romance isn't the main focus of the story. That doesn't stop it from 'technically' being one due to the female party members eventually garnering feelings for the same man who happens to be MC. The main question here is, can characters actually be good (well written/developed/interesting etc) despite being inside a harem plot thread?
Well...that depends on what the focus is. Are you looking for the interactions and relationship as the focus, or just the sex? Harem plots are almost exclusively about the MC sleeping with all of the others in the building, which are usually all opposite gendered, in succession. A romance plot can do some of the same things, closer to bordering on erotica, but not so heavy handed on the literal porn aspect of it. I guess you need to ask what your audience is you are looking for. Those looking for the well established harem plot is basically looking for you know what. Erotica a littleless so, but heavy on the sensual elements. Romance will be different of course too, further detaching from the physicality, but with its own levels of it as well. Then there's always literary fiction but i doubt your doing that route with this. What im getting at here is that any way you write it can be 'good,' it just depends on the audience you are going for. Each will be looking for their respective levels of comfort. Those looking for a harem story are usually looking for wish fulfillment sexual stories that border on or are porn. They can be erotica too, but that may be a disappointment to some of the audience if you use the term harem. You may also miss the intended group if you call it the wrong genre as well. Just figure out what you would like to do with it first and how much of a harem it would actually be.
Why not? Depends on the length of the story and the number of people in the harem though. Are you talking about litrpg novels or manga or...?
Sure it can. Read the Knights of Sidonia manga. By the time I left it, the MC was living with a Gauna girl, a robot girl, an intersex person (who becomes a girl) and the ship's XO. Yet the focus is only partly on that, and as much on the colonists' fight for survival against repeated Gauna attacks and the past of the ship's command crew.
I guessing I am going for a little bit of a harem, although it's purely satirical (and not in a 'mean' way either, more of a self awareness humor) which I plan to make clear in an author's note. There's only four girls (any more would be 'too many' in my book even for a harem) in the harem, and each of them like MC for different reasons, my big goal is for those reasons to be organic. I'm planning on putting three to five chapters of focus on each of the girls as they're added to the group. There's only one girl in the group that behaves like your typical harem female toward the protagonist, but that's part of the joke since she's usually drunk, when she's sober her actual personality comes out and that's (hopefully) going to be kind of interesting. My biggest concern is weather or not my girls boil down to "The __ one", at the end of the day many of my characters do when it comes to their 'defining' trait, but I usually try to add my own spin on it (For example, the MC of one of my fanfics is 'The Stoic' but he spends much of his time researching and trying to understand emotion to better himself as a person) to keep things interesting. Like how the 'drunk' one's personality is only that way because she's intoxicated and she's actually quite a badass while sober.