Agree, these are mere calculations and not reflective of true value (which may be both more or less). Also, in case of equity the market price or NAV (of mutual fund) is a result of collective wisdom of Market (which again can be right or not right, but its is open and collective). Idea is that as an investor, I would not buy an REIT just because it is at significant discount to book value because book value is itself arbitrary and not a result of collective wisdom and free market forces.
The share price of REIT is more reflective of true value and as your point 2 mentions the significance of “rent” here even in calculating the book value - Any investor buys the REIT for Rent yield and if you see in US currently interest rates are close to 0 and REITs have a yield of around 2-3%. Applying same delta to a 5% FD rate and a delta of 2% gives the result of REITs should currently trade at around 7% yield (this is not accurate and just for purpose of representation of my thoughts that REIT valuations depends solely on its Rent yield). So if you see the value or rather share price of REIT depends on rent yield and only rent yield (and so does the book value).
I think they are good investment in a falling interest rate scenario, but imagine if the rate cycle reverses and interest rates in India reaches back to say 8%, then in order for REIT to trade at yield of 10-11% either their rent yield should increase proportionally (booming office market) or its share price should fall proportionally (Like what happened in last 1 year during pandemic when interest rates fell and office rent market did not boom).
Also another important point I have in mind is that Real estate is a very capital intensive business. For growth, these REITs need to take debt. As investor, I generally keep away from large capital intensive business and where huge debt maybe needed because here the management decisions/interest rates and economy fluctuations play a role as big as the in general booming real estate market (primary reason why many people invest in Real estate or REIT and if they do it in their own personal capacity, they may not leverage the way the managers of REIT may do - unless of course if they are governed by any regulations on leverage/debt front and have the most ethical management concerned not just about growth of assets but also growth of yield and REITs share price.
Disc: Not invested, but interested. Tracking. Above are personal thoughts and I maybe wrong in my assessment. Not a recommendation to buy/sell.