This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
It is far worse to put java code (scriptlets) in JSPs.
An IDE is no substitute for an Intelligent Developer.
But to answer the original question: not at all. Remember, a JSP is simply a template for an HTML page. To the JSP processor, anything that's not a JSP construct is just template text that is completely ignored by the JSP engine and sent to the client verbatim.
Now, putting Java scriptlets into a JSP: that's not only a poor practice, but completely irresponsible at this point in time when we're coming up to the 10th, yes 10th, anniversary of JSP 2.0. Ten years is plenty of time for anyone to have come up to speed on the JSTL and EL and there is no excuse, none, nada, zero zilch, justification for still writing JSPs as if it were 2001.
As this is the JSP forum, we'll not debate it here, but that's all Java baggage that's being carried over. Sure there are rules that seem weird to Java folk, but in the context of the language itself make perfect sense.
It's certainly not perfect -- far from it -- but it's a good tool for its purpose.