Yes. It'll save you from doing so later if the module is ever becomes slated for removal from core. It's also useful for those analysing dependency trees.
Modules previously removed from core:
Archive::Extract
assertions
assertions::activate
assertions::compat
attrs
B::Asmdata
B::Assembler
B::Bblock
B::Bytecode
B::C
B::CC
B::Disassembler
B::Lint
B::Lint::Debug
B::Stackobj
B::Stash
Bundle::CPAN
ByteLoader
CPAN::API::HOWTO
CPAN::DeferedCode
CPANPLUS
CPANPLUS::Backend
CPANPLUS::Backend::RV
CPANPLUS::Config
CPANPLUS::Config::HomeEnv
CPANPLUS::Configure
CPANPLUS::Configure::Setup
CPANPLUS::Dist
CPANPLUS::Dist::Autobundle
CPANPLUS::Dist::Base
CPANPLUS::Dist::Build
CPANPLUS::Dist::Build::Constants
CPANPLUS::Dist::MM
CPANPLUS::Dist::Sample
CPANPLUS::Error
CPANPLUS::inc
CPANPLUS::Internals
CPANPLUS::Internals::Constants
CPANPLUS::Internals::Constants::Report
CPANPLUS::Internals::Extract
CPANPLUS::Internals::Fetch
CPANPLUS::Internals::Report
CPANPLUS::Internals::Search
CPANPLUS::Internals::Source
CPANPLUS::Internals::Source::Memory
CPANPLUS::Internals::Source::SQLite
CPANPLUS::Internals::Source::SQLite::Tie
CPANPLUS::Internals::Utils
CPANPLUS::Internals::Utils::Autoflush
CPANPLUS::Module
CPANPLUS::Module::Author
CPANPLUS::Module::Author::Fake
CPANPLUS::Module::Checksums
CPANPLUS::Module::Fake
CPANPLUS::Module::Signature
CPANPLUS::Selfupdate
CPANPLUS::Shell
CPANPLUS::Shell::Classic
CPANPLUS::Shell::Default
CPANPLUS::Shell::Default::Plugins::CustomSource
CPANPLUS::Shell::Default::Plugins::Remote
CPANPLUS::Shell::Default::Plugins::Source
Class::ISA
Compress::Zlib::Common
Compress::Zlib::Compress::Gzip::Constants
Compress::Zlib::Compress::Zip::Constants
Compress::Zlib::CompressPlugin::Deflate
Compress::Zlib::CompressPlugin::Identity
Compress::Zlib::File::GlobMapper
Compress::Zlib::FileConstants
Compress::Zlib::IO::Compress::Base
Compress::Zlib::IO::Compress::Deflate
Compress::Zlib::IO::Compress::Gzip
Compress::Zlib::IO::Compress::RawDeflate
Compress::Zlib::IO::Compress::Zip
Compress::Zlib::IO::Uncompress::AnyInflate
Compress::Zlib::IO::Uncompress::AnyUncompress
Compress::Zlib::IO::Uncompress::Base
Compress::Zlib::IO::Uncompress::Gunzip
Compress::Zlib::IO::Uncompress::Inflate
Compress::Zlib::IO::Uncompress::RawInflate
Compress::Zlib::IO::Uncompress::Unzip
Compress::Zlib::ParseParameters
Compress::Zlib::UncompressPlugin::Identity
Compress::Zlib::UncompressPlugin::Inflate
Devel::DProf
Devel::InnerPackage
Encode::Internal
Encode::iso10646_1
Encode::JP::Constants
Encode::JP::ISO_2022_JP
Encode::JP::JIS
Encode::JP::Tr
Encode::Tcl
Encode::Tcl::Escape
Encode::Tcl::Extended
Encode::Tcl::HanZi
Encode::Tcl::Table
Encode::usc2_le
Encode::utf8
Encode::XS
ExtUtils::MakeMaker::YAML
ExtUtils::MakeMaker::bytes
ExtUtils::MakeMaker::vmsish
Fatal
File::CheckTree
JNI
JPL::AutoLoader
JPL::Class
JPL::Compile
legacy
List::Util::PP
Locale::Constants
Log::Message
Log::Message::Config
Log::Message::Handlers
Log::Message::Item
Log::Message::Simple
Math::BigInt::Scalar
Module::Pluggable
Module::Pluggable::Object
OS2::DLL
OS2::ExtAttr
OS2::PrfDB
OS2::Process
OS2::REXX
Object::Accessor
PerlIO::Scalar
PerlIO::Via
Pod::LaTeX
Pod::Plainer
Scalar::Util::PP
Shell
SubstrHash
Switch
Sys::Syslog::win32::Win32
TAP::Parser::Source::Perl
TAP::Parser::SourceHandler::pgTAP
Term::UI
Term::UI::History
Test::Harness::Assert
Test::Harness::Iterator
Test::Harness::Point
Test::Harness::Point
Test::Harness::Results
Test::Harness::Straps
Test::Harness::Util
Text::Soundex
Thread::Signal
Thread::Specific
TieHash
Version::Requirements
XS::APItest::KeywordRPN
Comment on Re: Should I list core modules as dependencies?