Just to start off, I'm not a designer so it's important to set that context up front! I'm on Insights, specifically on Gameplay, so I'm responsible for things like data informing game balance, playtesting content in development, gathering feedback from players via surveys and labs, etc. I work closely with designers and the balance team, but I don't design anything - I gather data and sentiment on the stuff they make and work with them to help inform our decisions going forward.
So, I'd default to one of our designers around why Raze has this specific ult, but I can speak to it philosophically. Raze's ult is 6 points. It is very lethal, requires near-line of sight (has a small aoe, so you can hit people in corners, but you can't hit them through walls), and is on a tight time window after being equipped to be used. It's definitely sharp ability, but I personally don't feel it's fundamentally broken and can be used as a tactical tool to play around. Compared to other 6 point ults, like Brimstone who can ult across portions of the map safely to block vision, deny defuses/plants, and threaten lethal damage on an area, or Jett who can spend 6 point to get a premium-powered weapon that's usable all round and accurate while moving and shooting, Raze's ult doesn't feel super outsized in terms of power - it's gated in a lot more ways than other ults (line of sight, time limited), but makes up for it in potency (lethal damage!).
To your point on the vision of the game, in my mind it's a matter of perspective. When I look at Raze ult, I do think of it as a tactical tool. It can be used to trade up on enemies with better weapons during eco rounds, deny predictable play if enemies stage in the same areas round after round, or punish a 5-man push if they don't respect your ult and clump up on one angle. It definitely results in kills more than some of our other ults, but it's gated into specific windows in a way that I find myself thinking how to use it and play around it round to round.
None of this is to say you're wrong - we CARE about how you feel, and recognize that getting killed by a rocket launcher isn't the first thing you think of when you hear "tactical shooter". But, we've been playing with Raze internally for years and have felt that her kit does provide an interesting tactical texture to the game; she has lots of lethal pressure, but its constrained in a lot of other ways (tight time windows, range-gated, line of sight, etc.)
Once again - this is just my take, and I'm not a designer. But hopefully hearing some more of our perspectives on this stuff can help you all understand where we're coming from as we continue to have these conversations with you all. We hear you and care about your thoughts on this.