I would tend to say...

Even if you have the option to:
a) Press 1 = Flame Shock, do not advance for 2.0 seconds.
b) Press 2 = Lava Burst, do not advance for 3.0 seconds.
c) Press 3 = Chain Lightning, do not advance for 3.0 seconds.
d) Press 4 = Lightning Bolt, do not advance for 3.0 seconds.

Or whatever the specific timing you desire...
This is far sub-optimal, compared to a click castsequence.

With a click system, we are essentially setting up a priority system.
Where spell 1 will fire off every "x" seconds, determined by our commas.
And spell 2 fires off every "x" seconds, also determined by the commas.
Ditto for as many other spells as we want to include.
With a fall-through which fires off when everything else is on a comma stage (cooldown or dot ticking).

With fixed delays, you are still stuck with:
- A >> B >> C >> D..... Repeat.
But what happens when you want your actual order to be:
- A >> B >> C >> D >> D >> C >> B >> D >> C >> D >> B >> A...
IE, variable cooldowns, not a perfect sequence of 1234, 1234, 1234....

A click castsequence is good any time your spells have variable durations or recast delays.
The only time the fixed sequence is optimal, is when every spell is an instant cast, such as a Pally's 96969 sequence.

There isn't much difference in game effects, between a delay caused by the number of commas in a macro and a fixed software option, where the next step cannot occur for "x" seconds.
However, the game effect forces us to click at a consistent speed, while the software option hard codes it, no matter how quickly or slowly we click our keys.
I'm personally not comfortable with fixed duration delays, no matter what my spam speed is, but some are comfortable with that; consequently even if fixed delays were as strong as a click castsequence, I wouldn't go this route.
It will come down to a preference for a given user.