By hallucinate you mean, not knowing what/where you are or doing, in that particular moment? Then yes, one can use that word. The simplest analogy of here-now is when you are watching an exceptional movie (as per your taste) and you get lost in those moments of watching. The same phenomenon is apparent in observing other forms of arts (songs, paintings etc).

So, are such states hallucination? Every person (human being) knows for sure that they are real.

Do humans "hallucinate" what is in front of them? It's fairly well understood that our visual cortex is the product of evolution. So we will see things as they are meant to be seen, by our visual cortex. This is completely different from what is really there.

Well of course your brain is keeping a certain state, even while in complete meditation. So what is the point? It is not like reaching a certain meditative state would make you superior among others, or a super-human even. Many have suggested that people reaching such states eventually do return back, and for some, such states even dissipate eventually if they don't keep up with the practice.

Ultimately, the idea is that the state of 'here-now' (whether arrived through practice, observation or heck even induced through means of substance - though there are differences) is the state when You are not your mind anymore. So in that sense, looking at above suggestion about memory, I would simply ask: what is the need of a memory?