

Here is the thing about the fireplace.
On an old house like that where they burned wood and coal, it probably isn’t lined in any way. So it is raw brick without a ceramic “tile” going through it. Over time the mortar between the bricks deteriorate and creosote builds in the gaps between the bricks. That is a fire hazard and there is no way to remove that creosote. Using chemicals can dissolve the creosote, but then you also remove what is holding the bricks in place, which means the chimney structure is even more compromised and can cause collapse.
Selling a house with a known compromised chimney that is open and appears functional without disclosing the state of the chimney can open you up to legal issues. You can’t really feature the chimney/fireplace as part of the listing either, even if you disclose the state of it, because you will be dealing with lower offers.
So a gas burner, even a high efficiency one, can cause a fire hazard.
Leaving it open and just putting decorative wood on a log holder is a nightmare because creosote will fall down as the temperature changes and you may be constantly cleaning creosote or staining your carpet with difficult to remove stains. A lot of those old fireplaces are shallow and have the flue opening towards the front instead of being set back with a “smoke shelf” under it with a modern fireplace, so creosote can easily fall feet into the room.
Your options are to tear down the entire fireplace and chimney, ripping apart walls and spending tens of thousands of dollars, possibly reaching to the 5 figure range on a house like that. Alternatively you cap the top, throw some slate over the opening or wall it off and let some poor bastard in the future spend the money on getting a functioning chimney.
They made the practical choice, and I support it, even if it is not pretty.
The only viable option to maintain the look is to seal up the flue and then you have to coat over the firebox if you don’t want the soot stained brickwork exposed.
That is probably a coal burning fireplace so it is very shallow, most I have seen are 14" or less deep. It is kind of silly to have a little nook fake real fireplace. I would have just walled it off and been glad to lose an inch on one wall if I couldn’t afford to renovate my century house.