My hypothesis is that if you have old plain HTML forms, users are more likely to hover over elements and read tooltip texts giving more details about them. But if you style the forms to look new/fresh/cool/nice etc., people expect explanation texts and hints under or next to the fields much more and are less likely to discover the old HTML tooltips.
Result of this is that today you need to invest not just into styling of forms, but also into higher quality explanation texts, hint elements like question mark icons etc. People are having higher demands when seeing nicely styled form basically.
Somebody tried to prove this? Is there some kind of study available online? Or is just your experience same like the of mine?