Where are the old creature designs?

Whenever a new SW movie comes out there always seem to be fans asking "Where are the aliens from previous movies and why don't we see them in Disney era movies? I will try to answer this question by using my knowledge as a Star Wars fan and my working experience as a sculptor. The lack of old alien creatures is a mixture of multiple factors. Here are the most important ones.

1.) Star Wars has always preferred new designs over old designs:
Nowadays it is easy to throw all the alien species that appeared in the OT into one pot and consider them "old designs" but people often forget that 40 years ago these designs were all new. ANH introduced us to a bunch of alien creatures but none of them made it to ESB except for Chewbacca. In ROTJ the only reused designs are Chewbacca, Yoda and Jawas even though Jabba's palace is full of alien creatures. The now iconic Twi'lek, Mon Calamari and Sullustan for example did not appear on screen until the release of ROTJ. It was only with the release of the PT that Lucas started to re-introduce the "old aliens". However, the vast majority of SW creatures in the PT were new designs.

2.) Some designs aged badly:
The idea what an appealing design is and what it looks like is constantly changing. If you look at fashion in the 80s you will see that it looks kinda silly by todays standards. Likewise Gammoreans look silly by todays standards and it would require a fair amount of redesigning to no longer make them look outdated. Star Wars fans are known to be nitpicky so redesigning a character always puts the designer at risk of estranging the old audiences while sticking to old designs can estrange new audiences (think of Yoda in TLJ).

3.) Making replicas is extremely expensive:
When the OT was shot nobody could have possibly known that even 40 years later new Star Wars movies would be produced. The masks and animatronics were not designed to last for decades and most of them have deteriorated to a point, where they can no longer be used for filming. Already back when ROTS was shot they had to use multiple old moulds just to recreate Vader's suit and I can imagine that Vader's mask is one of the props most prominently featured in the OT. Since reusing the old maks isn't an option the artists would have to create them from scratch while simultaneously making sure that they look exactly like the old ones which often results in more work than a completely new design. There are similar problems with outdated 3D models and rigs which I won't get into detail here.

4.) Directors want artistic freedom:
The directors of Disney era SW movies have a surprising amount of freedom when it comes to picking creature and character designs. Their personal preference trumps the reusage of old designs which is evident when looking at TFA, R1 and TLJ which all featured mostly new designs. Unless a director has a taste for creature design similar to Lucas' we will continue to see a lot of new creatures. This desire of "doing your own thing" is not restricted to SW. Looking at the Harry Potter series for example we see vastly different interpretations of one of the same setting/character/creature between film 1 to 4. Only when David Yates took over (4 to present HP franchise films) we got to see more consistent designs.

5.) Most people won't even notice:
Here on the forums we often think of our understanding and knowledge of the franchise as a standard. In reality however most people watching SW movies can barely identify an Ewok or a Jawa. Of course, going through all the trouble to recreate old creatures is huge for a hardcore fan but it is a non-issue to most other viewers. At the end of the day they are more "casuals" than hardcore fans so guess who they focus on?

6.) It's more about the SW feel rather than a canoncially accurate appearence:
In Disney era movies we see many designs that are similar to perviously seen species. Ottegans for example are clearly reminiscent of Ithorians. They instantly feel like SW aliens but the designers did not have to update old moulds or 3D models. There are many "soft reboot" aliens throughout the Disney SW movies making sure that the typical SW feel is achieved without having to go through the trouble of browsing through dusty archives and contacting movie props collectors.

7.) There are actually quite a few old designs in the ST and anthology movies:
TFA had Mon Calamari, Jawas, a Wookie and Sullustans. R1 added Twi'lek, Aqualish and even Bib Fortuna's cousin Beezer. With the release of Solo we can be sure to see even more familiar faces such as Hutts and Rodians. Keep in mind how few species made it from one movie to the next in the OT. The numbers aren't that far off in the ST and anthology movies.

8.) Disney is already reusing their own designs:
In an interview JJ has stated his love for Vober Dand and how we are probably going to see him in future movies and sure enough we saw him again in TLJ. In both TFA and TLJ we saw the Urodel Bollie Prindel and a bunch of Tarsunts. With the return of JJ we will most certainly see a lot more aliens previously seen in the Disney era SW universe.

So these were the main reasons why there aren't more aliens from the OT in the new SW movies. If you know additional reasons or feel differently about it please let me know.