Agreed, Why anyone would be heavily invested in an artificially capped currency that most people can not use is beyond me.
Remember a fee market does not work. A fee market simply prices people out, it decides who can use and who cannot use Bitcoin.
It is not "beyond you" to understand this. It is pretty elementary.
1. You can understand pretty well the concept of abuse.
2. You can understand that not 100% of humanity is dependable to behave in a good manner, 24/7/365.
3. If you leave the option of free and totally unrestrained use of the blockchain then it's just a matter of time before the blockchain is bloated to infinity by some script kiddie who creates some script and lets it run continuously and adds tens / hundreds of gigabytes of spam, "for the lulz"...
4. You can now fully grasp that fees and "limitations" are what prevent system abuse that would have already rendered BTC a swift death.
5. If you have a better solution for the problem at hand, please present it.
The question you pose is actually reversed: Who would actually be invested in a joke currency that a script kiddie can render it useless for the lolz?
Miners have plenty of incentive to set their own min fees and spam filters, and they do/will.
They have the incentive but they are not configured accordingly. Not all of them. That's why dust/spam/no-fee and "stress test" txs get processed.
People seem to have a hard time understanding that max != actual. You think a tx spammer is just lying in wait for a limit increase to run their script? That 1MiB (that we haven't hit until now) is protecting the network from complete disaster?
The 1MB limit is definitely helping to prevent abuse. Otherwise the attack vector and the willing miners are there for exploitation in a 5MB, 10MB, 20MB block scenario.
As many of the 1MB4EVA crowd seem to be quite interested in Monero (completely tangentially of course), maybe that would be the best option for them. It would have a limited supply, meaning it would be a great store of value (wouldn't you agree brg444?), with complete built in fungibility. They could crank fees way up to keep the riff raff lolcows out, and their hardware and bandwidth requirements tiny... seems perfect.
I do not believe that BTC should stay at 1MB. If it was up to me, it would grow depending the actual organic growth of the network* and other considerations that have to do with security, centralization etc.
* by that I do not mean the number of transactions. This is a pretty useless metric if one can start issuing tens of thousands of txs.