My biggest argument is just what your edit says: designing some tedium to the game can be fun, its fun to do some work to get to a goal, it makes that goal that much sweeter. Plus the definition of tedium is different for everyone. I'd wager most people who were interested in a gregtech fusion reactor found it fun the first go around, but 10 worlds later found it tedious. I mean, MFR is considered one of the more 'fun' mods without much tedium, but how many times can you set up a planter and harvester before it also becomes tedious?
Here is where I would like to disagree with a few things, as my opinions differ.
Do keep in mind that I said 'opinions', nothing is inherently 'better' or 'worse' on an absolute scale. Value and worth are, inherently, subjective terms. Each person will have a differing view, although some or even many may share similar views. This does not invalidate your views, however by sharing opposing views, we may all find parts of the other side's arguments which have worth and merit to further consider, and so bring us closer to a greater understanding.
I, personally, have a really big problem with using bland and boring tedium to try and extend the 'shelf life' of a mod. However, there are ways to extend a tech progression and make it interesting. Let's take some examples, and I'll show you what I'm talking about.
I'd really rather not get into Gtech, so let's look at IC2-EX for now, and some of the changes that were implemented which I feel fall under the category of 'bland and boring tedium'.
First off, the Hammer and the Snips to make plates and wire. Yes, this allowed them to remove the Refined Iron, however it forced them to add in plates for every metal, so you actually end up with more items in the mod than previously. However, the mechanic of the hammer and the snips, particularly with their low damage values, is pure silliness. Then you get a machine, which runs on quite a bit of EU, which can automate this for you. But you need to make the hammer and the snips before you can make this machine. Then you've got a random hammer and a random pair of snips lying around your inventory that you will never use again. All to get you exactly where you were before.
Now then, I will admit that this is certainly a different methodology, however it doesn't really bring much to the enjoyment of the mod itself. It doesn't really introduce anything new other than a couple of new recipes you need to cycle things through and a couple of new items that will gather dust in your inventory once you get that machine up and running. It doesn't slow the process much, or make things interesting. It feels punitive rather than exploratory, to me.
Now let's use a counter-example of Thaumcraft 4.
Getting started with TC4 is by no means easy, it takes a bit of exploring with your Thaumometer to get all the right aspects to start your research. Your research can be somewhat guided by what aspects you start researching with, but there's always a random factor when you have multiple research options available tied to that aspect. You need to make a wand to start drawing essence from nodes to really start crafting anything with TC4.
However, unlike IC2, you are introducing new concepts and new mechanics. The scanning with the Thaumometer, for example, is a completely new and unique mechanic. The first wand you make will eventually become semi-obsolete, but it will ALWAYS have a use, if only in your Arcane Workbench grinding out smaller orders.
TC4 is just as difficult to progress in, probably harder in fact than even Gtech is. However, it does so in a far more entertaining manner, and draws you into the mechanics of the mod rather than making me go 'oh jeez, you mean I've now got to cycle them through another combine with a tool that breaks and needs to be replaced every time I look at it funny?'.
Thermal Expansion didn't really make things any 'easier', it required a good bit of infrastructure to get things like Tesseracts going, and the resource investment was not trivial. But what it -did- do that I appreciated was a massive reduction in computer and system resources required, and it did a lot to combat lag.
Does this make any sense to you?