I can think of 3 reasons why an interview would go like this.
The people in charge of the interview are crazy busy and may not have the time to deal with a full sit down interview.
They are not well organized and lack any interest in the interview.
Its the interviewers 1st time interviewing or they are still new to it.
The 2nd option is unlikely in my point of view. This is because you stated several positive facts about the company and with all those factors considered I am leaning more towards option 1.
There could be other factors but the 3 I listed are the ones I have encountered the most.
Its really hard to judge your working conditions based of of the interviewing staff. Sometimes the people planning or conducting the interview have no clue how to go about one. It may be their first time being the interviewer. They could be rushed due to some deadline that is more important than the interview at the moment. Or many other possibilities.
I would continue with the 2nd interview and not judge the working condition until you have actually spent time working there.
I have had an interview that in my opinion werewas conducted by people that didn't know the subject matter and a general lack of understanding of the field. I did get a job with the company and I really enjoyed my time there.
Your experience may vary but my point is don't judge a job by its interviewing process.