How is this 'having it both ways'? Members of Congress need to face the people every few years. If they are able to repeatedly win elections throughout their life I don't see that being a problem? Individual members have nowhere near the amount of power as a President or a Supreme Court Justice
I know what you mean but there is a significant problem with gerrymandering in the US system which means that often as long as you're of the appropriate party you've got a seat for life. The only real threat you face is having a primary challenger from your own party try and unseat you. So even though, in theory, you should face the electorate every two years meaning that if they're unhappy with you you'll get booted out, the reality is that that doesn't happen.
This is, of course, why you often end up with total lunatics in the House of Representatives because primary's are often closed to only those of the appropriate party affiliation and of those only the hardcore will actually turn up to vote. Meaning you need to be a lunatic to appeal to the small pool of voters who will choose the candidate.
All that being said the appropriate remedy would be to undo the gerrymandering but both parties tend to benefit from being able to sow up their constituencies as they see fit so never seems to be high on the agenda.
It's not just a high bar. I'd argue the method provided for changing the constitution is not at all appropriate for the modern age: I would expect that if you have a written constitution, the method for changing it ought to involve some participation by the voters - for example, that it can be changed by a super-majority in a referendum. But according to
https://www.whitehouse.gov/about-the-white-house/our-government/the-constitution/, US method for changing the constitution is a 2/3 vote in both houses of Congress plus a vote by the legislatures of 3/4 of the states. In other words, you need close to universal agreement amongst the ruling political parties, but absolutely no approval by the wider electorate.
I know what you mean but, of course, the counter argument would be that the US, like most, is a representative democracy, not a direct democracy, so representatives are elected to get on with the business of governing. Whatever the precise mechanism used (as there are a couple of different routes that can be taken) those representatives at Federal and State level are highly involved in proposing and ratifying the change and that is what they are sent to Congress or State Houses to do.
There is an argument to be made that, in the 21st century, when its possible to transmit information instantaneously and travel across the US in a matter of hours that the electorate should be more hands on than when the Constitution was written in the 18th century for sure. But I'm not convinced that the current process isn't fit for purpose but perhaps there is scope for a hybrid process where the existing methods of proposing an amendment continue as now (either 2/3rds of Congress propose the amendment or 2/3rds of the States apply to Congress for a convention to be held at which amendments can be proposed by the States) but then the ratification process requires the electorates of at least 3/4ths of the States to vote in favour.
All that being said, I suspect that there are bigger constitutional fish to fry than the process used to amend the Constitution!
I also find this worrying:
That would seem to imply that it will be impossible to fix the awful disproportionate way that Senate seats are allocated without the agreement of every single one of the small states that are currently over-represented.
I know what you mean but that is one of the key roles of the Senate. To provide all states, no matter their size, an equal voice in one of the houses of Congress. Which I do think has some merit as an idea. Whilst it does obviously lead to some perversity, Wyoming (population: 576k) has as much power in the Senate as Texas (population: 30.5m), at the same time it would seem unfair that somewhere like Wyoming would be totally drowned out by the larger States if both Houses were elected on a more proportional basis. After all Texas sends thirty-eight members to the House of Representatives to Wyoming's one!
I think the issue here is that many people aren't benefitting from the strong economy, or at least don't feel they are benefitting.
I think that latter point is perhaps the critical issue. On most metrics the US economy is doing pretty well at the moment. Inflation is perhaps a little higher than would be ideal (at around 3%) but unemployment is fairly low (4%), and growth is going well (2.8%) so the situation seems to be going quite well. But it seems clear that, for various complex reasons, that this headline good news isn't trickling down and being felt by those further down the food chain. I think that ends up driving quite a lot of the discontent that we've seen generally. People are being told that we've never had it so good (and, to be fair, in many respects we haven't!) but they don't feel like they're actually benefiting from these good times.