Actually if you look at how temples were treated in Biblical times - there were many restrictions about temple usage/attendance that resemble LDS teachings regarding temples today. 
 
Here is a quote from another website (fairmormon.org) that gives a good explanation: 
 
"Why are Mormon Temple ceremonies secret to the public when the Old Testament temple ceremonies were open to public knowledge?" 
 
"Large portions of LDS temple ceremonies are publicly discussed in church publications such as the Ensign, the History of the Church, and the Encyclopedia of Mormonism. There are, however, certain aspects of temple worship that are considered to be of such a sacred character that they are not to be viewed by, nor discussed with, the uninitiated. The same was true with the biblical temple of ancient Israel -- Gentiles were never allowed into the three main temple areas (outer court, holy place, holy of holies) and the entrances throughout the temple complex were guarded by porters and shielded by veils. The vast majority of the Israelites were never allowed to view the ordinances that took place in the temple proper (holy place, holy of holies)." 
 
"Many early Christian groups had ceremonies or services (frequently referred to as the "mysteries") that were only open to those who were faithful members in good standing. Would the critics also condemn them?" 
 
"Jesus also taught his apostles things which they were not permitted to teach to everyone, and this was done in private." 
 
"The Latter-day Saints are merely following a pattern of respect for holy things laid down by Jesus and the early Christians (Matt. 7:6). Latter-day Saints treasure this aspect of Christian life and worship, clearly spelled out in history and scripture."