The early Christians were small in number and often persecuted, so they couldn't build special buildings for their own use. Instead, they used whatever buildings were available to them when they came together–private homes, public halls, even synagogues (for many of the earliest Christians were also Jewish).
Only later, as they grew in number, did they have the ability and the legal right to build separate church buildings. In time, some of these became very elaborate (and you can still see many of these ancient cathedrals in Europe today). As Christians grew in number, they also occasionally took over buildings that had once been pagan temples, some of which were quite large.
I am not an architect, of course, nor can I tell you what your church should do about its new building. If you have concerns, however, you should share them with those who are involved in planning this project. But be a good listener, also; they may see a new building as a tool to make the church more effective in its outreach.
The Bible says, "So whether you eat or drink or whatever you do, do it all for the glory of God" (1 Corinthians 10:31). May this principle guide not only your own life but your church as it plans for the future.