I'm not sure what this means. If a slim fit looks good on you, it is appropriate for any occasion.
The too slim is actually a valid concern.
I believe people do not put enough consideration into how they dress for these interviews. It's more than what someone thinks looks good and what is 'in' at the time.
dermaway brings up a good point, and here is why: The people who are doing the interviewing went through this process in the 90s, 80s...even the 70s. Suit styles were different back then. Suit fitting seems to mirror general public fashion trends. If you look back to the 60s, suits were nicely fitted. Hit the 80's...baggy saggy clothes everywhere. Suits didn't get baggy, but they were definitely loose fit. Could you find a suit with the word 'slim' on the label in the 80s? I think the only fashion thing that was slim at the time was 'slim ties'. haha.
Anyway, back to the point...think about what looks good, but think about what the interviewer will think. We're back to slimmer clothes being in style (despite obesity trends). As pointed out above, it's actually getting ridic a bit imo...soon suit pants are going to actually be capri/yoga pants.
Interviewers are used to what they know...you are playing to them. I'm not saying wear an 80s suit style, but just be careful about going to extreme with modern trends...there is a limit to how 'slim-esque' a suit can be...totally valid point. Relatively slim fit...sure, extreme slim to the point of FASHION FORWARD...no.
There is a common trend in all the things some of us older fogies are trying to get across.
For instance, what I said above about no double breasted or french cuffs...that is TOO formal for this type of interview. While they are not trendy and are classic styles, they suffer the same effect of trendy styles which southern IM pointed out above: "This person is too formal, who does he think he is? Overdressing to impress? well I'm not impressed."
Again, just stopping at 'how do I look?' isn't even enough. One has to think about the context of what will transpire at the interview/event and what people may think of them. Sorry, people do care what others think of them regardless of what anyone says...it's part of what makes us human.