Foot Protection - Water shoes are designed for activities that involve more active pursuits where a quick change from dry to watery environment happens. They are specially designed to protect your feet from bumps, spikes, sharp rocks and abrasions while making sure the sediments and rocks don't get in.
Traction- Since "water" shoes are obviously designed to be used underwater, manufacturers have considered the importance of sole grips to avoid slipping in sliding surfaces. Having excellent traction aids a lot in friction which in turn helps your feet stay gripped on the ground (where it should be).
Quick-drying- Quick-drying water shoes are more comfortable and more durable than typical shoes that get wet. Remember: water shoes don't keep your feet dry. If you want that, wear rainboots. Instead, water shoes let your feet dry quickly after getting wet.
Breathable- Water shoes aren't as breathable as sandals are. On hot summer days when you aren't planning on canoeing or kayaking or wading into the ocean, your feet would appreciate sandals instead.
Chill- Water shoes won't keep your feet warm. If you're planning on taking a dip in cool water, look at a pair of dive boots instead.
Long walks- Water shoes are not built for long day hikes - they just don't offer the support or protection you need. So pull on your hiking boots for wilderness trails and save your water shoes for the water.