It is so interesting to hear everyone's excellent points of view. I feel that these dessert parties offer value to people for different reasons and are an expense to be considered along with all of the other (very high) expenses at WDW. I have done the MK Tomorrowland Terrace seated party, the MK Plaza Garden View standing party and the Epcot Frozen Ever After party. In each case, the parties were selected during extremely busy times of year, New Years Eve and Christmas. At those times, the parties were essential to me having a good time, and were an excellent "value" at times, as follows:
1. During busy times, the parties are almost a "must" for me. I had heart surgery some time back, love the MK, love the holidays, love fireworks and yet I can't physically handle many many hours on my feet in the midst of crowd mayhem. But I'm not going to give it up! Ha ha. As such, I go in late afternoon, enjoy the MK, have an early dinner, continue to enjoy the MK, and then (very gratefully) retreat to Tomorrowland Terrace with my table and chair, coffee, a bit of dessert, fun atmosphere, and >>dedicated bathroom<<. From my TT "perch" up above the crowd, watching the fireworks is awesome. I can catch my breath, relax, rejuvenate, without feeling that I have to leave the park because I'm "done in". The Plaza Garden standing view is the better view... but... you're standing. Plaza is great for families with kids who can kind of spread out and move around without fear of the kids getting lost. My teens prefer Plaza view. We all loved the Frozen Ever After party (crowded Spring Break week). It was fun, better food/drink, the party had great savory options, veggies/dip, etc. the view of Illuminations was perfect, and riding the Tier 1 Frozen ride afterward was a bonus. No dedicated bathroom. I would not do it for Epcot Forever (which is a temporary fill-in show).
2. Is the cost high? Yes. But I WOULD do a dessert party again at certain times. Examples of other "high cost" items that I would NOT do again include: Cinderella's Royal Table, Ohana, the Snow White Dinner at Artist Point (Wilderness lodge). From my perspective, those were once and done. CRT I enjoyed. Ohana and Snow White (I can't remember it's actual name) I did not enjoy. I would trade those pricey dinners for a quick serve dinner + dessert party in an instant. Plus, those dinners are so looooong. You pay all that money to be at Disney and then spend 1-2 hours sitting in a restaurant? Hmm. Time is money. With dessert parties, you're in the park, and you're part of the whole park ambiance.
3. During "regular" visits, I don't do the parties. Example: This past Oct, Halloween party #1, I walked right up to the Partners statue just before showtime. Halloween party #2, I got a table out front of the Plaza and had an awesome seated view. Kids grabbed ice cream from the parlor. Some of the projections were obstructed, but I don't really care about watching every detail of the projections. I prefer more of the "overall view" of the show. The downside of the projections is that you can almost accidentally find yourself watching them like you'd watch a TV, and if you do that, you somewhat miss the "overall effect". Also in Oct, my family and I watched HEA from a hammock on the beach at the Poly and thought it was great, even though we couldn't see any of the projection detail. I've also watched from the boat dock at the Grand Floridian, excellent view.