But that's not really an inadequacy of shopping as gameplay, the true fault lies in the rather simplistic set of customization options for each mech and how the shopping is very neatly organized by "levels".
You are correct that differentiating the parts more would have required the player to think about his choices more and would have added depth to the shopping minigame.
However, there is an issue with that. Even though
Front Mission's shopping was very simple, it still required a very large amount of time, simply by virtue of the amount of parts you had to buy and the number of mecha you had to do it for. You spent at least 15% of your time shopping, possibly much more, depending on how much you optimized and how fast you are with the game pad. (It was way more than 15% for me, since I wanted it all perfect). If there had actually been tough choices involved, that would have taken even longer.
That's why I think this game is such a good example. It really tests how much shopping you're willing to put up with to get your stat increases. For example, if you bought new gear right before the final mission you'd potentially be dealing with 17 units (all can participate), 6(ish) parts each, plus a minor amount of comparison and testing.
The solution to this is to increase the number of items with unique properties, item sets that work well together (in obvious and not-so-obvious combinations), not divide items into clear level sets, implement various reasons to keep old items instead of replacing them with +1 variants and so on - in other words to increase the complexity and customization options enough that each player can dress up their little computer people/mechs/aliens/whatever according to their preferred playstyle, instead of shopping being something that might as well be streamlined into an UPGRADE EVERYTHING FOR 1000 GOLD button that would just raise the level of your equipment according to the current game level and send you off to fight appropriately leveled mobs to earn the next 1000 gold ad infinitum.
The principles your describe are certainly correct, but if shopping in
Front Mission had actually required thought, I think that I'd still have become mired in a shopping and inventory management hell. Upgrades were simply too frequent (upgrades for every part every few battles) and there was simply too much that I needed to buy. It was just too much effort to put up with for a mediocre tactical RPG.
One has to ask, what is the point of making the player shop for 15 minutes to get stat bonuses to all the parts of his mech, then raising the enemy's stats to balance things out? The player is not stronger relative to his enemies, but he has wasted 15 minutes. The only thing that changed is that some numbers went up.
I propose that we'd be better off entirely eliminating the mundane upgrading type of shopping, implementing the "
UPGRADE EVERYTHING FOR 1000 GOLD" button if necessary and reserving shopping and other tedious forms of inventory manipulation for a smaller number of items that actually have a tactically significant impact on the character's capabilities.
There isn't really any way to fix the fact that the actual process of shopping is tedious, but if it is rare and there are interesting choices involved, the player probably won't mind too much.