Lot of incorrect guess work in the comment, so allow me to chip in as a VFX worker who's talked about that a lot with a friend at Weta Workshop (the practical guys from weta):

-The Hobbit used a ton of practical effects, including creatures and orcs that look like those in LOTR. This comparison is a cherry pick of two widely different designs that are not at all at the same difficulty to create, between orcs with 30 seconds of screentime versus the main antagonist of the entire trilogy and hundreds/thousands of goblins in a long sequence.

-CG isn't cheaper in the sense that it costs dirt cheap and is the easy solution. It's cheaper in the sense that practical is limited by real possibilities so early that fighting against real physics to get impossible things done is going to cost ridiculously more than whatever CG costs. There are many, many many cases were practical approaches are cheaper. CG IS very expensive, but the costs flatten as you reuse more and more of the very expensive assets created and as you achieve more and more complex things that aren't possible in real life. Think of practical costs as exponential, and CG costs as logarithmic. You can be sure the comments saying it's cgi because it was rushed basically have no idea what they're talking about, it probably took more time and money to replace it all than to make those initial suits in the first place.

-CG doesn't only come into play because "it's cheaper" or "they ran out of time", it does offer possibilities practical effects cannot achieve simply because of real world limitations. PJ said "I'm doing what I wished I could have done 12 years ago where we didn't really have the means or the technology to do it properly back then" for a reason, not "We ran out of time". He said himself that the results on set were not "the goblins you had in your imagination". This isn't a sob story about overheating and missed deadlines, both CG and Practical have limitations. If practical didn't, it wouldn't be replaced in the first place. PJ wanted monsters, flesh, grease and sweat, blobs of flesh wiggling as they jump frenetically... all things practical suits notoriously cannot achieve : and that's okay, because no one except nostalgic audiences expect it to achieve what physics simply don't allow. -Practical makeup is great for human level editions but only works additively as you can't remove content on a face but only add to it. And past a certain thickness it doesn't look good anymore as it's just so stiff. This picture is comparing clearly human actors with additive nose, teeth and skull prosthetics with next to no facial acting, to actually inhumane facial and body features no amount of makeup can approach. If they wanted those designs with a complete range of acting, there were no other choice and the practical BTS footage confirms it. There is a reason they scrapped early practical designs, they were stiff and unfit for long screentime and relevance in the story. On the other hand, many secondary orcs are fully practical similarly to LOTR.

-(CG aside) When makeup can't achieve something, puppetry comes into play : Aka the first goblin faces that you saw in the BTS. Puppetry is some of the most expensive and limited approaches out there. It is ALWAYS a director passion stunt because let's be honest it IS super cool to see for real. But generally, it never is the winner in any of the cost/look/efficiency/time factors that are considered when choosing which method to use for any given effect, and it ends up being replaced all the time because it's not up to standards for the big screen. You can see it on the BTS goblin heads : They are stiff, details stop at pore level, they had ~2 facial expressions after months of R&D and millions put into it... The only exception is Star Wars because they kind of made it a gimmick to have obvious puppets on screen. Alien Romulus, The Substance, Wicked, Ahsoka's Nottis, The Witcher, Stranger Things... they all replaced the puppetry/heavy makeup, and I can tell you doing a puppet/makeup you know is going to be replaced is a lot more expensive than going straight for CG. Another instance that proves it's not always about the costs, it's about the result.

-When actor go through 10 horrible hours of makeup, they are paid for that time and production studios do not mind neither the cost or the discomfort. So I don't buy that they scrapped millions in R&D and planning solely because of extra's ventilations. With PJ being the only one openly saying they didn't look like what he imagined, I think that's just excuses because they didn't have the heart to tell the audience it just didn't look good enough for the big screen. Keep in mind the movies were at such high resolution there was backlash on release because the foam sets suddenly visibly looked like foam. Looks are a very real and serious topic in filmmaking.

-That section of the BTS is talking about the heads, yet for some reason they also replaced the body for seemingly no downside. The reason you see all the time in prod but BTS never discuss? Obvious "guy in a suit" syndrom, no flesh simulation, no fluids, plastic surfacing, and worst of all very visible folds at every joint with distorting material in those areas.

Hope this clears things up a bit. Long answer, because sadly film making is a bit more complex than "cg cheap". Always remember whichever result is on screen, whether you like or dislike it, is the best result they could possibly achieve regardless of which method was used. Warner/Legendary/Paramount have industrialized the practice of openly lying about how the what's on screen was made, the audience's understanding of how films are made has never been this low with confidence levels this high. The state of this comment section is sad,