The design characteristics of Bitcoin makes it more suitable for use as a store of wealth rather than as a medium of exchange.
wrong. everything about bitcoin makes it a medium of exchange or a currency instead of being a store of wealth. and everything that has been done to bitcoin so far has been done to make it a better and more efficient currency while keeping it decentralized such as addition of lightning network.
1. Easier/Faster Mining
2. No transaction fees
3. A Small Portable Blockchain
these only look good in writing. when it comes to actually implementing these you will encounter real problems. and just saying it should be like this and that and listing things is not enough you should talk about HOW and What would be the downside of each thing you sacrifice.
The difficulty of solving a block is not what protects the blockchain from a 51% attack, the hash rate of the network does. The difficulty only effects the block rate, which limits coin production and minimizes race conditions that threaten to compromise consensus. But an excessive difficulty prohibits miners from working competitively, resulting in a concentration of cooperative mining power and the potential for shenanigans by pool operators. The mining difficulty should be kept as low as possible without jeopardizing consensus so as to permit and encourage miners to mine competitively using less expensive hardware.
you completely misunderstood what difficulty is!
difficulty is a variable that is changing at predefined intervals (2016 blocks for bitcoin) to match the hash rate. which means if you have high hashing power your difficulty will go up and vice versa.
No Transaction Fees
If the block reward stays proportional to the mining difficulty, there is no need for transaction fees.
ok, good in theory and works in a perfect world. but lets come back to the real world that we live in.
what will you do to prevent people from spamming the network? in less than 5 minutes you can write a script that keeps creating transactions and pushes them to the network constantly filling the blocks up. there is no fee in your coin and there is nothing preventing such people from doing so. your network is clogged and nobody can make a transaction anymore.
(there is NANO with 0 fees but you are talking about a mineable coin based on bitcoin here)
A Small Portable Blockchain
In order to keep the blockchain within a size limit that keeps it portable, old blocks must be deleted at the trailing end as new blocks are added at the leading end. Blocks will then have a lifespan that depends on the block rate. This introduces the possibly of destroying coins. Users will need to spend or recycle their coins before they get too old or risk losing them. This is precisely why a medium of exchange is unsuitable as a store of wealth.
this will not work simply because you are forcing everyone to make a transaction every X amount of time meaning you are limiting the number of users your coin can have. now with all those useless transactions they are filling the blocks, the blocks which were already being spammed by free transactions and they won't even get their tx confirmed so double problem. they can't confirm their tx and their time is running out because their coins will be invalid soon!!!