Euphemism for "non-useful"

I was just about to tell someone how something "wouldn't really be much useful" if they leave it the way it is — which is like a much more polite version of useless, but I just couldn't find the word. I'm guessing I just don't know it.

What is an idiomatic euphemism for non-useful?

EDIT:

It was actually an answer to a question, and I was wondering how I would say this answer is not really useful without hurting the person.

According to this list of British "euphemisms"...

"Very interesting" means "I don't agree/I don't believe you"

(the hapless American assumes the Brit means "I am impressed", so the euphemism has worked!). But I personally think it's a good way of saying "Although what you say is interesting, and might be useful in some other context, it has no practical value in relation to my current problem."

Older Americans may recall Rowan & Martin's Laugh-In, featuring the catchphrase

"Very interesting ... but stupid!"

"This answer doesn't suit (or doesn't fit) my needs." In my opinion, this puts the perception of shortcoming on my needs instead of their answer.

The appropriate euphemism for "completely useless but still quite nice" is entirely decorative. See for example its use on Wikipedia, for Dutch Gable and this review of some headphones.

Edit: Another option might be well-intentioned. This would even be applicable for the edited version of this question; that is, the "useless" thing is an answer to a question.

"Not exactly the thing" or "not quite it".