Hi Andy,
Thanks for going back and finishing and giving us some new feedback! It's very much appreciated :D If you don't mind, I thought I'd respond to each of your points below a little so you can see where we think we might take each one
1) Rewarding Battles - Yes, we completely agree and was very much something we wanted to address with this prototype but just didn't have time to both implement a system to do this / figure out which one would be the best option. As this aspiring to be 'simulated' MMO, our thinking in terms of the card system is to very much bring in a more RPG element to the actual card system in terms of some sort of card customisation. Whether this be through something like XP gained per card used in battle and then the cards level up or gaining special items that you can then use to upgrade the cards, change attributes of them, increase their attack power, add a status effect etc we're not sure on the exact method we're with you on trying to make battles as rewarding as possible :D
2) D.CP limit - if we're honest, we had very little time to test the balancing of the game, we were both testing, writing code, setting up events and drawing art pretty much right through until the 8am deadline (that's how tight it was :O) so admittedly this just wasn't paid much attention. The same goes for item prices in the shop (most of it was guesswork if we're honest!) and we were well off the mark haha.
3) Elements - Yes, you are correct they function in a similar way to MMBN and yes, this isn't communicated to the player very well (or at all to be honest, again, something we can fix and address but just didn't have the time).
4) Battle presentation - you are right in that this is a little tricky :( we did implement a 2x zoom feature in our code (not available to you unfortunately) but felt that this was too zoomed in and some sort of middle ground would have been better however that's hard to do and maintain pixel perfect scaling for the art. We did feel though that when fullscreen was used this did mitigate the issue somewhat however can appreciate that it's not perfect.
Hopefully that kind of lets you know where we might be going with this and hopefully some of this would address your issues you have. Again, thanks very much for such detailed feedback, it means a lot :D
Glad you found the final boss interesting. Our programmer worked hard to try and ensure that the battle would be more interesting and different to the norm to try and demonstrate some of the potential we could have for variety in battle :D
TLDR; We agree with all your points and we definitely have some ideas on how we can address them, unfortunately the lack of time hindered us from implementing any of them