I think ship sizes are fine. The bigger they are, the more they could block out and make things harder to see. You can make a bunch more boats now compared to early 2000s, too, in terms of higher pop count maxes… So higher propensity to block more stuff.
But I just don’t like the thought of bigger ships. I think they’re fine 
They’ll look too big, clunky, and ugly, imo
Probably because I’ve played and loved AoE2 for years, I don’t mind ships looking too small compared to units. Unlike building proportions in AoE4, which I really dislike
PS: I really wish AoE2:DE water was a deeper darker blue like that, and could be modded with more deep shades. It helps the world feel more real and treacherous, with deep oceans, lakes, rivers, and ponds. It’s impossible to make the 3D water look like a really deep blue. However, 2D water is a step in right direction with coloring and saturation, just not nearly close enough. I recommend disabling 3D water.if you want darker blues.
I had a thread/posts about water here with some AoC and AoK water screens at bottom of post, too:
And more water talk, if curious → Improve water look, effects, and animals possible for AoE2?