It really pains me to see investors complaining about how they lost their hard earned money or savings in a project. But the bitter truth is that most of these people are lazy to do their research and they just get in a project for the promised ROI or because some analyst hyped the project for them.
The main reason why you should consider putting your money in any project (either ICO, IEO or STO) should be because you are totally convinced that the project have an innovative idea with a working product that solves an existing problem (very important) and with a very good and experienced team to lead it to success.
An example is a project I won't mention, a lot of people got into it not because of their personal research but because one analyst ranked it in "Hall of Fame", of which if they had done their research they would have realized it was a ticking time bomb. And it exploded 15 minutes after the tokens were unlocked.
I agree with you, IEO makes things easy for you the exchange will do the research and if it passed the criteria people will think that it is a legit project, but investors should not stop there, they should still do their own research it's double-checking money is involved here, it's better to check again and again.
At least IEO was doing better rather than STO or ICO in the past.
Not all of IEOs is legit and only IEO that listed on the major exchange site that can be called as a legit. Remember about there are only some major exchange sites while the rest placed at the medium or low reputation as exchange site.
We need to do more than double check