The way I see it, you destroy a perfectly useable piece of kit, pass its enchant to another for a limited benefit.
Eh ? Why ? How does this power up weapons/armour in the long run. I just don't get it, sorry.
The higher your enchanting skill and the more perks you have in Enchanter etc. The more powerful your enchantments are.
Say you use two handed weapons and heavy armor but you find a piece of light armor with fortify two-handed. Its rather useless to you. So you disenchanted it and can then enchant your own equipment with it. When your enchanting skill is low the items you make will be weaker then most of what you find. But eventually your enchantments will become equal to your far beyond anything you can find. Plus you can make it on the fly. Once you learn an enchantment you've learned it forever and can make as many items with that enchantment as you wish.
I'll use my Nord warrior Odin as an example of what can be done with enchantment
Helm: Fortify Archery by 40% and Waterbreathing
Armor: Fortify Health by 62 Points and Stanima regeneration by 31%
Gloves: Fortify Archery and Two-Handed by 40%
Boots: Fortify Stamina by 62 Points and Stamina Regeneration by 31%
Ring: Increase Magic Reistance by 25% and Fortify Two-handed by 40%
Amulet:Fortify Stamina by 62 Points and Stamina Regeneration by 31%
I have another set of items with fortify smithing 25% each for a total of 100% which greatly enhances the power of my weapons and the protection of my armor.