Normal was always pretty useless, it's just the introduction of arsenal stations that cemented its place at the bottom of the barrel. Why use normal equipment - designed for versatility - when you could change to specialized gear every level?

As for the main idea, -1. Normal defense and damage need to be fixed, but this isn't the way.

It'd go against the progression of the game to have normal defense simply 'be useful for everything'. Note that I am speaking as a 2* Elite solo player that regularly farms Tier 1 content mainly wearing Wolver Set, currently working on investing in gearsets to begin fighting regularly in Tier 2 content.

Part 1 of the game: You're getting your feet wet, and though there is equipment to experiment with, generally with most monsters dealing non-specialized damage, pure normal defense is usually the way to go.

Part 2 of the game: You've progressed, and now enemies are beginning to deal split between normal and specialized. Though, and I paraphrase from the mission tutorials, "Normal defense is still a somewhat viable option", the specialized damage is now encouraging the use of specialized equipment to help deal with, among other things, the growing issue of status ailments (Freeze is a downright nasty problem in this regard if caught unprepared).

Part 3 of the game: You're at the high end of the game, and monsters are beginning to deal mostly specialized damage. Every bit of specialized defense matters at this point, and even then it's a rough ride. There is no room left for normal defense in most situations.

What's the point of all this, you might ask? Since Klipik-Forum already mentioned that you can change gear almost every level, it pretty much comes down to time, money, and training sinks.

Besides, there IS equipment that does what you're asking for. As an example, the Magic Cloak 2* set provides a little less normal defense and minor status resistances for one element compared to a specialized elemental equipment of that star level, but provides more elemental defense and provides resistance for multiple elements. This easily blows away the Spiral Plate Mail set (and with its negatives, there's little reason to actually try this suit on anyway aside from thrashing Tier 1 content without worry, but I'd prefer Wolver Set right now for that), and is a good alternative to slip into once you've fought in the Cobalt Armor set long enough. However, there's still Shadow damage to worry about, so you'll have to invest in the Skelly Suit set for that as well.

This is the game's way of telling you that you'll have to start branching out in order to progress. If you don't like the way the system is, maybe this isn't the kind of game for you? It's a serious question to consider at this point, as continuing to rely on normal defense through the progression is asking for a lot of trouble, based on the game design, and will only give you more headache and stress as you keep playing.