it’s mainly used in emergencies, as it can be risky
Trying to come up with an in-universe reason for why the transporter room still exists, I wondered if perhaps site-to-site just uses more energy somehow. That maybe directing a transporter beam to a transporter pad to handle the reintegration process was more efficient. That while they could technically reintegrate the matter stream anywhere within range (which they obviously can, since they can beam someone to/from any arbitrary spot on a nearby planet), a transporter pad is just better equipped to handle the reintegration, so it used less energy and they preferred to use it when not an emergency.
I believe there was a line in Discovery about how a certain captain prohibits site-to-site transport to the same level within the ship because of the energy waste. Transporting between levels of the ship is fine, and has made the turbolift obsolete, but transporting between two rooms on the same floor is a waste of energy compared to just walking there. Though I assume it was probably encouraged in emergencies.
https://memory-alpha.fandom.com/wiki/Site-to-site_transport
Basically the sensor technology wasn’t good enough for a while. And even later in tng time, it’s mainly used in emergencies, as it can be risky
Trying to come up with an in-universe reason for why the transporter room still exists, I wondered if perhaps site-to-site just uses more energy somehow. That maybe directing a transporter beam to a transporter pad to handle the reintegration process was more efficient. That while they could technically reintegrate the matter stream anywhere within range (which they obviously can, since they can beam someone to/from any arbitrary spot on a nearby planet), a transporter pad is just better equipped to handle the reintegration, so it used less energy and they preferred to use it when not an emergency.
I believe there was a line in Discovery about how a certain captain prohibits site-to-site transport to the same level within the ship because of the energy waste. Transporting between levels of the ship is fine, and has made the turbolift obsolete, but transporting between two rooms on the same floor is a waste of energy compared to just walking there. Though I assume it was probably encouraged in emergencies.