This depends very much on the context. Using something like `readFile` without carefully exhausting it is absolutely a mistake in a long lived application or a high volume web server, and in a setting like that reaching for that kind of an interface and hoping future modifications preserve the "reads to exhaustion in reasonable time" is questionable at best.

On the other hand, in a program that handles a small number of files and doesn't live long after file access anyway (say a small script to do grab a couple things, crunch a few numbers, and throw the result at pandoc), there's nothing wrong with lazy IO and it can be quite convenient.