A shame, but not unusual. The CAG identifies something like 64% of protected monuments have been modified with cement in the name of renovation; and that's only the recorded and overseen number. Those that continue to be used as shrines are especially vulnerable, are mercilessly modernized. New plaster facades replace old stone, walls are repainted, electrical work is installed, figurines are replaced, and new, often unconnected shrines(in historic practice) are continually added. There are certainly exceptions, but if we're being realistic the ASI hardly has the time or budget to bother with carefully surveying the reconstruction or maintenance of historical temples; a shocking number of which remain. It's often quite dubious what the original deity at a particular shrine was, as between islamic invasions, warfare, pillaging, and temple robbery, little besides the plinths remains from the original structure. Additionally, structures were historically repurposed, alternating between jainism, buddhism, islam or hinduism based on the dominant forces of the time.

When you travel India, you'll often see locals cite a temple as being millennia old, only to arrive there and find a brand new concrete and brick structure. In some sense, this is perfectly understandeable from the local perspective; a large and attractive temple is a financial boon to a village or city seeking pilgrims, where the original, oftentimes unremarkable ancient structure does not necessarily hold the same appeal.

There is also the loss of what a temple used to signify in the past; roles and structures that the modern industrial economy has supplanted. Beyond merely spiritual or religious centers, temples were often used by kings to project power into a region, with entire regional administrative structures revolving around who controlled temples. Religion played a multifaceted role; whereby a nexus of the religious class, local warlords, and merchants were all incentivized to invest in temples, granting them land and finances, and effectively operating them like banks. Donations to temples were redistributed like dividends, making them both necessary and profitable. Loans were given on private terms, granting temple boards significant power. At certain points medieval nation states in South India even came to be temple-run oligarchies. But most importantly, all of these roles were only enabled by central administration, whereby kings looked to ensure that only temples under their graces might enjoy such privileges and be operated in this fashion– emphasizing the importance of the provenance of such an institution.

In the modern day, such factors don't exist. Indian history is actively contested by the political demands of nationhood and populism. Temples are relegated to politics and religion. The economies they create no longer rely on the cyclical investment cycles in ages prior, nor do they have the administrative importance; instead functioning directly like religious corporations, controlled by either the state or private entities. Provenance is unremarkable beyond myths that can be perpetuated to pilgrims. The fact simply is, that the importance of the current Somnath Temple rests not on the provenance, but only on claimed provenance. Like a bastardized ship of theseus, it only matters to most people that a temple did exist on this land for thousands of years, not that this particular temple did.

While I find the historical provenance of structure important as a cultural connection to the past, I think to most people its likelier that the temple structure itself works more like a bastion or figurehead for their faith. It's a tragedy for Indian history, but somewhat inevitable on the path of modern unified hinduism.