FD changed their business model. Completely within their rights. LEP owners got nothing for thier purchase of extra content that others had to bay for. and FD doesn't feel as thought they need do anything. Welcome to capitalism at its finest!
An LEP owner too (from Kickstarter) I have "a feeling" the idea might be to try to get away from the pre-purchase model, which requires your customers to have full 110% faith that an early update in a pre-paid set, isn't representative of the whole expansion. I think it's a hang over from kickstart partly and that developing a game with as much scope as ED would be a major undertaking for even a large publishing house, let alone a medium sized, self publishing developer.
If I was FDev I would be trying to use 2018 as both opportunity to consolidate the base game (Beyond) but I would also 'want' (not saying it's definitely possible though) to develop 4.0 in parallel. Then when it comes time for 4.0, I think benefits in selling that as a full expansion, available there and then in finished form.
Because it comes in piecemeal I feel even excellent content will almost always meet with a sceptical reception when pre-paid, especially by people who don't see any need to demonstrate faith in the developer. Needs maybe must, if your game is going from standing start, however if you can get development ahead of the customer base then at least people know what they're getting, when they decide to buy or don't buy the expansion.
It can be reviewed fairly then, in the round, rather than by a genuinely uninformed and probably reactionary steam community setting the agenda on one side and equally unsure white knights, fighting the other corner. Any overt criticism of the game, or the way it's developing can (for example) be seen (by me) as an undermining attack on the game I invested in / backed at kickstart if it puts even one person off playing it.