To be honest, I kind of feel like they're starting to rush product at this juncture in order to get as much profit as they can out of the IP and card game before what they perceive as it's inevitable demise (and, to be honest, they're not fully wrong).
Right now, the Dragon Ball Super card game is anchored to the Super IP and other affiliates of Super (even somewhat including Dokkan Battle). But I imagine they perceive a large part of the CG's popularity being born from hype, and with that comes the fear that once the anime concludes the popularity of the game will subside and any extra product they have lined up, licensed, produced and printed will become net negatives. Excess money spent where the audience has already left.
On the other hand, you also have the potential sales you can net out of the anime's following. For example, once the ToP ends, they'll probably want a few pieces of product freshly being released so that they can advertise it at the time, as well as include character's or elements from it's ending. After that, if we get a 2018 movie, they'll want a pack to be ready for release around that period, and they'll want to tie promos and other exclusives to the event. In this vein, they'd want product ready, licensed, produced, and announced for every up and coming beat surrounding the Dragon Ball IP (including the release of games carrying a lot of hype; FighterZ [not totally sure if they've taken advantage of it, it would just be a really good idea from a business perspective if you say, put forward a deal of getting a deck and a copy of the game for a discount]). In this regard, this is a ridiculously vital time for the card game, as Super is reaching the end of a crucial arc and we have a ridiculous amount of Dragon Ball product lined up over the course of the year.
Additionally, this early on in a card game's life, you really want to keep discussion surrounding it alive and very, very loud. Especially considering the overall climate of card games, where the big 3 are starting to lose their neigh-monopoly on the industry. You CAN subsidize this with events, special announcements, daily card reveals, on-going communication with the fanbase and etc., but the best method will always be new content as it brings deck crafting and actual purchases with it. This ensures you stay relevant, and that you keep people coming back even between the lulls of other IPs (which you can use as leverage to generate a bigger player-base).
All of the above reasons why it makes business sense said, I actually think their playing their hand a bit too hard right now, and players like you are kind of evidence of this fact. I feel like there is a slight misunderstanding of their audience and player-base, who are mostly long-term fans of Dragon Ball and are here for the long run. By rushing out so much product so quickly, they hurt their potential sales as player's come to be more overwhelmed. Also, I think that by introducing so much product so quickly, there isn't really enough time for quality control, and they're blowing their load in what is their second phase.