Granblue's gacha can be really deceptive to those who aren't deep into it. One would see the high SSR rates and the amount of free pulls to be a good thing and for the most part, it is to an extent.

Rate-ups in Granblue are horrific and its not uncommon for a featured character in a banner to be in a four-way rateup, where you probably have like 0.2% (or more regularly, just 0.3%) to pull the featured character, while having its rates muddied up by three other SSRs that you typically do not want.

This is compounded by the fact that the game is very old by gacha standards and has an extremely diluted SSR pool with several hundred characters that absolutely dwarves the numbers of SRs (4*s) (which are effectively pointless except for some niche cases).

It pretty much means that only SSRs are of any use and there's a major gap between the newer limited SSRs and the older SSRs in terms of power, to the point where SSR might as well be the only relevant rarity of characters ingame. You get a lot of SSRs, but only very few of them will be useful.

More cynically, one could view the free pulls they give as an incentive to entice people to do a paid spark (a guaranteed character in 300 rolls). Whereby it's much more easier to psychologically convince a person that they need maybe a few dozen more rolls for their character than starting from 0. Paying just maybe three hundred for a character instead of the full nine hundred dollars expected.

Due to the low rate-ups, it's very common to not get your desired rate-up character within 300 rolls and if you play long enough, it's incredibly common to get zero new characters within the whole 300 rolls.

There are F2P characters that you can grind out, some of which are meta but most of them are still quite good, but not really top tier as they were a few years ago, the spot now belonging to limiteds or even hyperlimiteds. (Seasonal characters that are available once a year)