When it comes to strokes, a line is a box

[getho]

I've been meaning to ask this for the last 10 years or so 😁

Line tool: it's not really a line is it? It's a very narrow box.  Which is fine, most of the time. Unless you want a dotted or dashed line, when it becomes a dog's dinner.

So yes you can use the path tool to make a non-enclosed path, but I'm left thinking - and asking here - that surely this isn't how it was designed?  That adobe wouldn't have left something so clunky for so long, and that it must be idiot user error. Please tell me I'm an idiot and how to draw a dashed or dotted line with the line tool that doesn't look like it's been made with powerpoint.

[c.pfaffenbichler]

The Line Tool is old. 

Shape Layers Strokes are younger. 

Photoshop’s vector capabilities are limited. 

So I recommend (as you already indicated) just to use the Pen Tool to create a Shape Layer with an open two-point-path for a Vector Mask. 

Edit: And for more complex line-design switching to Illustrator might be useful. 

[getho]

Sigh.  Photoshop reached its peak of usability around 1999. I cant help feeling after that that the people who were running the show, weren't using it.  They started playing fast and loose with muscle memory, and tagging things on rather than integrating them properly.  I used to rave to anyone that would listen about photoshop, now I'm more likely to be raving mad.  Except generative fill. That sh#! is immense 😋

[c.pfaffenbichler]

Sigh.  Photoshop reached its peak of usability around 1999. 

Smart Objects were introduced in Photoshop CS2 (which must have been around 2006) and Smart Filters in Photoshop CS3, so that statement seems nonsensical to me. 

[getho]

I wasn't talking about a particular feature, I was saying that its peak usability was even earlier and it has been going downhill ever since - implementing features but not well and then never updating them (blur gallery!), or taking something that worked, albeit in a slightly clunky way, and "improving it" but actually making the usability worse.  The worst offender for me was changing the modifier keys for transforms. Lets reprogram 20 years of muscle memory, yay! 

[c.pfaffenbichler]

They started playing fast and loose with muscle memory

That touches on a sour point for me … not being able to select Whites, Neutrals and Blacks in Selective Color Adjustments Layers via keyboard shortcuts anymore is annoying to me.