There really is no right or wrong answer here, just personal preferences. I look at the decision to add Park Hopper to tickets in several factors below...
1) How many days are you planning to go to the parks?
Park Hopper costs $55 per person for the duration of your trip. Person who is planning to go to DLR for just 2 days will pay roughly (ticket prices might change) $145 per day with Park Hopper. Person who is planning to go 4 days ($98.75) or 5 days ($83) will see a dramatic drop in per day prices with adding Park Hopper. In my opinion, value wise, easier to justify adding Park Hopper if per day ticket costs are $83 (5 day tickets) compared to $145 (2 day tickets) or $122.33 (3 day tickets).
2) How many times are you planning to visit DLR over the next couple of years?
If you're a DLR veteran and go fairly often, than you've already done everything that both parks offer and will most likely already have a favorites to ride lists. In those cases, maybe your perfect day is to start the day in DL, hop over to DCA in the afternoon to do the few rides you like there (GotG, Soarin, RSR) and then hop back to DL to finish the day. If you fall in this category, then the cost of Park Hopping would be justified, as it tailors to your favorite DLR experience.
If this is going to be your first DLR trip or you only visit every several years. Than you might prefer to spend a whole day per park over Park Hopping. This decision is made even easier if they're not offering Maxpass/Fastpass services. As if I'm in this category and I want to have the full DLR experience and go on every ride, then Park Hopper might not make sense. Without Maxpass/Fastpass (this might change in the future), it would be hard to do everything both parks offer in a single day, leaving no time or hardly any time to hop to the other park.
3) How do you see DCA, is it a half day park to you? Are you a fan of Marvel?
I saw DCA as a half day park and was considering getting Park Hopper for my July visit. Especially since I didn't want to waste time if we completed DCA by 3-4pm or so. Although when I heard Avengers Campus would be opening on June 4th.....THAT CHANGED EVERYTHING!!! LOL
Personally, my family is a HUGE fan of Marvel and as a family we make an event out of seeing all the MCU movies as they come out. My 3 kids all love those movies, tv shows and characters. With Avengers Campus now open, I now see DCA as a full day park. Between the following that Avengers Campus offers....
* GotG ride and WS ride (if lucky to get boarding pass)
* All the different character shows from Spidey stunt show, Dr. Strange sanctum show, fight sequences with Black Widow/Black Panther vs Task Master show and the Dora Milaje show
* Eating food on campus between Pym's Test Kitchen and grabbing shawarma from one of two Shawarma Palace carts on campus
* Grabbing different drinks from Pym's Tasting Lab and trying different treats like Cosmic Cream Orb/Sweet Spiral Churro
* Visit to the new Stage 17 at Avengers Campus, which is simply the greatest collection of Marvel collectables that I've ever seen
With all that, we will probably spend 3-4 hours just in AC and possibly more, as we want to see AC at night time too. My 3 kids already told me they want to spend all their "souvenir" money for our entire California trip in Stage 17, so I'm expecting to spend at least close to an hour there just shopping and browsing.
On the flip side, if you don't care about Marvel and don't care about Avengers Campus outside of riding GotG or WS rides, then you might still consider DCA a half day park and want to think about getting Park Hoppers to go to
Disneyland once you're done with DCA.
4) How important is riding both Virtual Que rides RotR and WS multiple times to you?
Virtual Ques are really a lottery system and if you have Park Hopper, it allows you two chances to ride both rides in a single day...…instead of just once in a one park per day ticket. To have better chances to ride both those rides might be worth the price of Park Hopper to some people, so you have to factor that in also.
Personally, I'm going with a 2 day/single park ticket for my family of 5, as we only just have 2 full days in our Anaheim leg of our trip. In the end, budget wise, I had to choose between getting a Park Hopper ($55 per person) or putting that amount towards a 1 day ticket at Universal Studios on our Los Angeles leg of our trip. We decided going to Universal would be more fun than having the option to Park Hop.
This will be our first trip to DLR and doing tons of research before our July visit. We are going early in the morning when parks open and staying till they close. Even though this is our first DLR trip, I'm a WDW veteran and pretty sure we can do everything that we wanted to do on those days. Only stressful items is dealing with the Virtual Ques but I've been practicing and constantly been getting through. I'll try on both days at 7am and 12pm to get VQ reserved for Rise and WS. Hoping for a bit of Disney magic on those two days!