/click doesn't have any inherent advantage, other than allowing large macros that wouldn't otherwise fit in a standard 255 character macro. It also adds modularity, so you can sub in an out a spell simply by dragging macros in and out of the buttons that you are /clicking. There's also a visual element, when you are tuning the macro to your key spamming rate, you can watch your cooldowns, and if your /click sequence is hitting them immediately after they are off of CD, you are all set, otherwise, adjust as necessary.

you can do the same concept of a /click macro in a regular macro,

/castsequence spell,,,,,,,,,,,,,,,,,,,,,
/castsequence spell,,,,,,,,,,,
/castsequence spell,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,

etc etc. when a sequence encounters a comma, it will pass to the next spell, allowing you to create artificial cooldowns, based on how fast you spam the key. /click just gives you one master button that initiates each sequence in its own macro and spot on your action bar. It also lets you do some creative things with targeting, as each macro can have separate targeting like one of the sequences can be targeted at the characters target (hex for example) but the rest of the macro can be using focustarget.