Quote Originally Posted by Foxhound438 View Post
Sure, but it's not like a cleric not bringing protection from energy is going to have their level 3 spell slots sprinting 10' a round at something that can crawl away prone at 15'. Not having the right niche spell doesn't prevent you from leveraging your spells at all, but an encounter that starts with 30 or 40' between you and enemies makes your ranger's entire flagship build defining feature that holds all of the build value for several of your levels do nothing for 3 or 4 rounds if you happened to think the boat adventure would have fights in the water when the enemy instead just jumps on to your boat.

For longstrider: See OP. Spending spell slots to do that all the time is not going to be good, and waiting until combat starts means you have to be an entire turn behind when fighting starts just to have your extremely slow octopus still need to spend actions to catch up with something merely walking away.
Why would you be doing this all of the time? The only reaon you would ever take Beast of the Sea is if you're doing underwater shenanigans, in case those shenanigans happen to depart on land unexpectantly your beast can still breathe and move on land so you're not completely screwed. You're at a disadvantage, but then again you're at a significant advantage in the water too. If you were locked into your choice I'd totally agree, but you're not so I don't see the big deal. The Beast Master gets to rock under water if it comes up, that's good, if you're trying to use a water centric creature on land regularly that isn't the stat block's problem, it's a significant tactical error on the most fundamental level.

The point of me brining up Longstrider was to highlight that you aren't completely up a certain creek during dry season. It lasts an hour and is a first level slot with no need to concentrate, if you are in the niche scneario (which is what this should be) you can patch the speed. At no point should this be losing you and turns personally or should it be costing your beast dashing for 4 rounds, combat that opens up at 35-40' leaves most melee centric builds at a disadvantage on turn 1 anyway.

Summary: It exists for the same reason Water Breathing and the amphibious option of Alter Self does, it gives you options. If you choose to lock yourself into those options, or utilise them at the wrong time then that falls on you, not the option.