In 2017, keen investors saw the bullish market and invested in any ICO in sight.
Fast forward to 2018, and most of these ICOs are dead, dying, or a scam.

So, what is the difference beetween ICO 2017 and ICO 2018?
You have stated the obvious difference. In 2017 ico are sold out quickly, in 2018 scam ico are many legit ones couldn't raise their softcap even if it has a unique idea.