With ketchup (and mustard, mayo, etc.), squeezable bottles are way more convenient. Gone are the days of wanting to get X amount of ketchup out of the bottle but ending up with either 0X or 10X.

Aside from the ketchup dispensing utility, you also escape tedious discussions about the best way to get ketchup out of a glass bottle. Do you tap the side? Shake the bottle? Angle it? Smack the bottom? Just sit there patiently? Warm it up? Stick a knife in it? You can be pretty sure that if you use any of these methods, someone is going to tell you about one of the others.