I understand where you're coming from. I also understand where the critics are coming from. That doesn't mean I think what the animators are doing is blasphemous for the following reasons.
1) Exaggerated, easy to draw characters are nothing new to animation. They've been around since pretty much the beginning. Felix the Cat, Betty Boop, Mickey Mouse, etc. and they make resurgences every few decades, Animaniacs, Ren & Stimpy, Powerpuff Girls, The Grimm Adventures of Billy and Mandy, etc. Animators know that it's a great art style to build off of when you want to tell humorous and or light hearted stories. All of that is en vogue right now, which is fine, trends are cyclical.
2) Trying to be efficient and saving time and money in animation is also nothing new. The classic Hanna-Barbera cartoons are a great example, just look at Super Friends or The Herculoids in particular. I understand why people get upset with some of the more recent animation techniques looking cheap, but even compared to the lower budget stuff from a few decades ago, we've come a long way.
2a) As an aside, people tend remember cartoons being better than they really were. For example, it's kind of popular to criticize Teen Titans Go! for being so cheap compared to the original series. I watched the original series quite a few times. I own the whole series on DVD. It doesn't hold up as well as our memories would like us to think. The first season in particular suffered from very simple sounds and animation low in background details. Lots of cartoons don't hold up as well as we remember. I think DC's Timmverse and Samurai Jack are two very good exceptions.
3) Most importantly though, this is just a cartoon series. Something someone is making to tell a story and to make a corporation money. They have control over the property, they can do what they want with it. Once again, I understand why people might not like the art style, but the creators of the series want to tell a different kind of story and the new art style matches the tone I think they're probably gonna take. It's not the end of the world. The original cartoons still exist and just because there is something new that has come about, it doesn't mean what was ceases to be. If something isn't your cup of tea and you fear it runs the risk of ruining your impressions of what you love, ignore it. I've joked on here before that The Matrix Sequels and the Star Wars Prequels were never made and that Iron Man 3 and Fallout 4 are both high budget fan projects and not official canon.
If there is one thing I've learned from comics, it's that sometimes people are gonna take properties we love and take them in directions we don't want them to go. It's fun to gripe a bit about it here and there, but it's important to exercise detachment. If we love a property so much that changing it in such a way causes us to feel grief and frustration, we need to step back and really consider whether or not our relationships with what we consume are being healthy.