I think it would be very nice if ODBC-Connections to a SQL-Server would preserve:
a) The Primary Key constraint while exporting.
b) Constraints like default values while exporting.
c) Extended properties like 'MS_Description' while exporting.
d) Auto value/IDENTITY while exporting.

And also b) + c) while importing or linking tables.
While a) + d) still works (sometimes) while importing or linking, it does not work in a one to one fashion.

The Microsoft SQL Server Migration Assistant for Access (32-Bit) is, unfortunately, buggy (or completely broken after v7.3.0) and extremely slow to open even medium-sized databases.

Once upon a time, this used to work fine. I still have old tables, that contain these extended attributes from the old Upsize Assistant:
AggregateType, AllowMultipleValues, AllowValueListEdits, AllowZeroLength, AppendOnly, Attributes, Collatinrder, ColumnHidden, ColumnOrder, ColumnWidth, DataUpdatable, DateCreated, DefaultValue, DisplayViewsOnSharePointSite, FilterOnLoad, GUID, HideNewField, LastUpdated, MSBoundColumn, MSColumnCount, MSColumnHeads, MSColumnWidths, MSDecimalPlaces, MSDefaultView, MSDisplayControl, MSFilter, MSFormat, MSIMEMode, MSIMESentMode, MSInputMask, MSLimitToList, MSListRows, MSListWidth, MSOrderByOn, MSOrientation, MSRowSource, MS_RowSourceType, Name, OrderByOnLoad, OrdinalPosition, RecordCount, Required, ShowDatePicker, ShowOnlyRowSourceValues, Size, SourceField, SourceTable, TextAlign, TextFormat, TotalsRow, Type, UnicodeCompression, ValidationRule, ValidationText