Yerr, I wasn't being realistic, really. Just wanted to show that even Tier IV Materia does matter.

Edit: To illustrate my point.
If
Dervy's weights for Ninjas are to be believed...
Splitting half of your materia into Det and Crit to account for random stat cap shenanigans -
Full Tier IVs would be worth 26.5 DPS
Full Tier Vs would be worth 41.4 DPS
A pair of Kannagi are worth 1105.6 DPS
Upgrading to Points of the Sephirot (worth 1135.8 DPS) from Kannagi nets you 30.2 DPS, worth slightly more than a full Tier IV setup, but a fair bit less than a full Tier V setup.
Upgrading to the Torrent Kris (worth 1178.4 DPS) from the Points of the Sephirot nets you 42.6 DPS, worth significantly more compared to a Tier IV setup, but just above a Tier V setup.
Upgrading to Augmented Torrent Kris (worth 1204.2 DPS) from the Torrent Kris nets you 25.8 DPS, worth less than both ranks of Materia setups.
Finally, upgrading to Midan Metal Daggers (worth 1216.2 DPS) from the Augmented Torrent Kris nets you 12 DPS, worth even less than the previous upgrade.
Essentially, not bothering to use Materia at all is akin to skipping weapon upgrades. And that's not even getting into the potential of crafted items holding up to five materia each
.
