Personal preference really. Arguments can be made for each point of view
I only rarely shut mine down cept to clean it unless nobody is going to be using it for a day or more. I use "my" sleep time to run all my AV scans and updates.
That way I can review everything the next morning when Im drinking my coffee.
in a way yes...regarding desktops, if the microsoft power management system wasn't so mangled it wouldn't be so bad to use hibernate/suspend or sleep mode...as it is, people tend to leave applications running when they put the system into suspend mode and things get messy from there...native windows processes don't do too bad with sleep mode though.
putting a laptop in hibernate/suspend or sleep mode is asking for a crashed hard drive...since the heads don't park...i see it every single day and the first question is "why did that happen?"...it's like resting a record player needle on top of a record, bump it and you have a nice scratch...stratch a disk platter and you have a bad drive...that's not to say it couldn't happen even with the system powered down but, the chances are greatly increased when you don't power the system down...and there is also the open applications issue that springs up after prolonged periods of suspend and sleep mode, some programs just can't take being stuck in memory for prolonged periods.
once ssd drives get lower in cost and become more mainstream, drive crashes from shock will be few and far between...until then, even with manufacturer "shock prevention" programs, don't bump it.
the only system i let run 24/7 is my fedora linux box, and even that gets rebooted every week to clear the memory buffer and cycle the junk logs...windows systems get shut down and i never use suspend or sleep mode...except when testing with a work system.